Alkali-soluble polymer and polymerizable composition thereof

ABSTRACT

A polymer, which contains a structural unit having a carboxyl group represented by the following formula (1) at a side chain of the structural unit, wherein node position is formed, when the polymer is dissolved in an alkali aqueous solution having a pH of 10 or more and kept at 25° C. for 60 days:  
                 
 
wherein R 1  represents a hydrogen atom or a methyl group; R 2  represents an (n+1)-valent organic linking group containing an ester group represented by —O(C═O)—; A represents an oxygen atom or NR 3 —; R 3  represents a hydrogen atom, or an monovalent hydrocarbon group having from 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 10/900,309, filed on Jul.28, 2004, which claims priority from Japanese Patent Application No.2003-202919, filed Jul. 29, 2003. The entire disclosures of the priorapplications, application Ser. No. 10/900,309 and Japanese PatentApplication No. 2003-202919 are hereby incorporated by reference.

DISCLOSURE OF THE INVENITON

1. Technical Field of the Invention

The present invention relates to a polymerizable composition and a novelalkali-soluble polymer to be used in the composition. Precisely, theinvention relates to a polymerizable composition suitable for theimage-recording layer of negative lithographic printing plateprecursors, and to an alkali-soluble polymer which is well soluble inalkali aqueous solution and which is to be in the polymerizablecomposition.

2. Background of the Invention

Heretofore, PS plates having an oleophilic photosensitive resin layerformed on a hydrophilic support have been widely used for lithographicprinting plate precursors. For making printing plates from them,generally employed is a method of mask-exposing (surface-exposing) theprecursor via a lith film followed by dissolving and removing thenon-image area to obtain a deired printing plate. Recently, digitalcomputing technologies have become much popularized for electronicallyprocessing image information, and accumulating and outputting theprocessed data by the use of computers. Various new-type imageoutputting systems that correspond to such digital technologies have nowbeen put into practical use. As a result, a computer-to-plate (CTP)technique is desired that comprises scanning high-directivity light suchas laser light in accordance with digitalized image information data fordirect production of printing plates not via lith films, and it is nowan important technical theme to obtain lithographic printing plateprecursors suitable to it.

For such scanning-exposable lithographic printing plate precursors, astructure has been proposed, comprising an oleophilic photosensitiveresin layer (hereinafter referred to as photosensitive layer orrecording layer) that contains a photosensitive compound capable ofgenerating an active species such as radical or Broensted acid throughlaser exposure, formed on a hydrophilic support, and its commercialproducts are now available on the market. The lithographic printingplate precursor of the type is laser-scanned on the basis of digitalinformation to generate the active species, then the recording layertherein undergoes physical or chemical changes owing to the effect ofthe active species, thereby having an insoluble area, and then this isdeveloped to give a negative lithographic printing plate. In particular,the lithographic printing plate precursor of a type having, formed on ahydrophilic support thereof, a photopolymerizable recording layer thatcontains a high-performance photopolymerization initiator, anaddition-polymerizable ethylenic unsaturated compound and an alkalideveloper-soluble binder polymer, and optionally oxygen-blockingprotective layer has various advantages in that its producibility ishigh, it may be developed in a simplified manner, its resolution is highand the ink acceptability of the printing plate from it is good, andtherefore the precursor may give a printing plate having desiredprinting capabilities.

Heretofore, for the binder polymer to constitute the recording layer,used are organic polymers soluble in alkali developer, such asmethacrylic acid copolymers, acrylic acid copolymers, itaconic acidcopolymers, crotonic acid copolymers, maleic acid copolymers,partially-esterified maleic acid copolymers (for example, seeJP-B59-44615, JP-B54-34327, JP-B 58-12577, JP-B 54-25957, JP-A 54-92723,JP-A 59-53836, JP-A 59-71048, and JP-A2002-40652). In lithographicprinting plate precursors having a recording layer that contains such anordinary binder polymer, the solubility in alkali of the binder polymerin the non-image area tends to be insufficient. In particular, carboxylgroup-having polymers of good alkali solubility are favorably used fromthe viewpoint of rapid developability. However, since the carboxyl groupcontains an ester bond in the linking group moiety to the terminalcarboxyl group (—COOH) in the polymer, and since the ester bond moietyis hydrolyzed with time in developer, the polymer loses the terminalcarboxyl group that is an alkali-soluble site. As a result, the binderpolymer solubility in developer lowers, and the binder polymer oncedissolved in developer during development therein may deposit to formdevelopment sediment, and it may impart a great deal of load to printingsystems, or the deposited development sediment may adhere to printingplates to cause stains in prints. To that effect, the polymer bindershave many problems.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the drawbacks inthe related art mentioned above, and its object is to provide apolymerizable composition favorable for image-recording layers ofnegative lithographic printing plate precursors, not producingdevelopment sediment in developer during development therein, and toprovide an alkali-soluble polymer to be contained in such a developablecomposition.

We, the present inventors have assiduously studied to attain the objectas above, and, as a result, have found that, when an alkali-solublepolymer having specific physical properties is used, then theabove-mentioned object can be attained. On the basis of this finding, wehave completed the present invention.

Specifically, the alkali-soluble polymer of the invention ischaracterized in that it contains a structural unit having a carboxylgroup represented by the following formula (1) at a side chain of thestructural unit, wherein no deposition is formed, when the polymer isdissolved in an alkali aqueous solution having a pH of 10 or more andkept at room temperature for 60 days. The wording “no deposition isformed” as referred to herein means that, when the polymer is stored inan atmosphere at 25° C. for 60 days, no polymer deposition is seen invisual observation.

In formula (1), R¹ represents a hydrogen atom or a methyl group; R²represents an (n+1)-valent organic linking group containing an estergroup of —O(C═O)—; A represents an oxygen atom or NR³—; R³ represents ahydrogen atom, or a monovalent hydrocarbon group having from 1 to 10carbon atoms; and n indicates an integer of from 1 to 5.

One preferred embodiment of the alkali-soluble polymer contains astructural unit having a carboxyl group represented by the followingformula (1) at a side chain of the structural unit; and which comprisesa functional group represented by the following formula (2) at a sidechain of the polymer, the functional group being capable of giving anacid group through hydrolysis with alkali:

wherein in formula (1), R¹ represents a hydrogen atom or a methyl group;R² represents an (n+1)-valent organic linking group containing an estergroup represented by —O(C═O)—; A represents an oxygen atom or NR³—; R³represents a hydrogen atom, or an monovalent hydrocarbon group havingfrom 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5;and in formula (2), Q represents a linking group that links X¹ to a mainchain of the polymer; X¹ represents a protective group hydrolyzable withan alkali aqueous solution having a pH of 10 or more; and when thefunctional group represented by the formula (2) gives -Q-OH afterhydrolysis, the -Q-OH is an acid group having a pKa of 10 or less.

More preferably, the functional group represented by the formula (2) isa functional group represented by the following formula (3):

wherein A¹ represents an aromatic group or a cyclo group (cycloalkane,or cycloalkene group); n indicates an integer selected from 1 to 5; X²represents —NR¹R², —SR³, or —OR⁴; R¹ to R⁴ each independently representsa substituent composed of at least one or more atoms selected from agroup consisting of a hydrogen atom, a carbon atom, an oxygen atom, anitrogen atom, a sulfur atom and a halogen atom; Y represents a singlebond, —O—, or —NR⁵—; R⁵ represents a hydrogen atom or a hydrocarbonatom.

The invention also provides an alkali-soluble polymer, which contains astructural unit having a carboxyl group represented by the followingformula (1) at a side chain of the structural unit, and which comprisesan acid group represented by the following formula (4) having an aciddissociation constant (pKa) of from 0 to 11 at a side chain of thepolymer:

 P—X³-(A²-H)_(m)  (4)

wherein in formula (1), R¹ represents a hydrogen atom or a methyl group;R² represents an (n+1)-valent organic linking group containing an estergroup represented by —O(C═O)—; A represents an oxygen atom or NR³—; R³represents a hydrogen atom, or an monovalent hydrocarbon group havingfrom 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5;and in formula (4), X³ represents a single bond that directly links to amain chain of the polymer, or a linking group selected from a groupconsisting of a carboxylic acid ester group (—COO—), an amido group(—CONH—), a hydrocarbon group and an ether group (—O— or —S—); A²-Hrepresents a partial structure that functions as an acid group having anacid dissociation constant (pKa) of from 0 to 11; and m indicates aninteger of from 1 to 5.

The invention further provides an alkali-soluble polymer, which containsa structural unit having a carboxyl group represented by the followingformula (1) at a side chain of the structural unit, and which comprisesan assistant group for dissolution in an alkali aqueous solution at aside chain of the polymer, wherein no deposition is formed, when thepolymer is dissolved in an alkali aqueous solution having a pH of 10 ormore and kept at room temperature for 60 days:

wherein R¹ represents a hydrogen atom or a methyl group; R² representsan (n+1)-valent organic linking group containing an ester grouprepresented by —O(C═O)—; A represents an oxygen atom or NR³—; R³represents a hydrogen atom, or an monovalent hydrocarbon group havingfrom 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5.

The polymerizable composition of the invention is characterized in thatit contains (A) an alkali-soluble polymer of the invention mentionedabove, (B) an ethylenic unsaturated bond-having compound and (C) acompound of generating a radical by light or heat.

Though not clear, the effect of the invention could be presumed asfollows:

The alkali-soluble polymer of the invention has a terminal carboxylgroup, and is characterized in that the ester bond therein is preventedfrom being hydrolyzed with time to cause polymer deposition with time.In the first embodiment thereof, the alkali-soluble polymer of theinvention has a structural unit having a carboxyl group of formula (1)at a side chain of the structural unit and has, in a side chain of thepolymer, a functional group of formula (2) capable of giving an acidgroup through hydrolysis with an aqueous alkali solution (developer)(the functional group may be hereinunder referred to as “specificfunctional group”) Therefore, it is believed that the polymer couldstill have good alkali-solubility because of the action of the acidgroup formed through hydrolysis of the side chain structure of formula(2), even after the terminal carboxyl group of the polymer has partlydisappeared in an aqueous alkali solution such as alkali developer.Accordingly, it is believed that, when the polymerizable compositionthat contains the polymer of the type is used in the recording layer oflithographic printing plate precursors, then the alkali-solubility ofthe recording layer could improve, and, as a result, the binder polymercould be prevented from depositing (to form development sediment) indeveloper during development therein.

In the second embodiment of the alkali-soluble polymer of the invention,the side chain structure of formula (4) is an acid group having an aciddissociation constant (pKa) of from 0 to 11, and it does not have ahydrolyzable linking moiety like the carboxyl group in the structuralunits of formula (1) therein. Therefore, the polymer of the type mayexhibit its alkali-solubility that is always stable even in aqueousalkali solution, and may keep its solubility in alkali. As a result, itis believed that the polymer may be prevented from depositing with timeto form development sediment in alkali developer.

Accordingly, the lithographic printing plate precursor comprising thealkali-soluble polymer in the recording layer thereof is, even whencontinuously developed in an automatic developing machine, effectivelyprevented from having development sediment to be caused by polymerdeposition in developer.

DETAILED DESCRIPTION OF THE INVENTION

The alkali-soluble polymer and the polymerizable composition comprisingit of the invention are described in detail hereinunder.

[Alkali-Soluble Polymer]

The alkali-soluble polymer of the invention is characterized in that itcontains a structural unit having a carboxyl group of formula (1) (itmay be also called a carboxyl group-branched structural unit) and that,when dissolved in an aqueous alkali solution having a pH of at least 10and left at room temperature (25° C.) for 60 days, it forms nodeposition.

In formula (1), R¹ represents a hydrogen atom or a methyl group; R²represents an (n+1)-valent organic linking group containing an estergroup of —O(C═O)—; A represents an oxygen atom or NR³—; R³ represents ahydrogen atom, or an monovalent hydrocarbon group having from 1 to 10carbon atoms; and n indicates an integer of from 1 to 5.

The means of preventing the deposition with time of the alkali-solublepolymer having a structure of formula (1) in aqueous alkali solution isnot specifically defined, so far as it may effectively prevent thereduction in the solubility of the polymer owing to the disappearancewith time of the alkali-soluble group, carboxyl group from the polymer.For example, it includes introduction of an additional functional groupcapable of changing in aqueous alkali solution to exhibitalkali-solubility therein, into the polymer; introduction thereinto ofan additional functional group having high alkali-solubility and capableof increasing the solubility of the polymer as a whole; or introductionthereinto of a structure not functioning as an alkali-solubilizing groupby itself but capable of increasing the solubility of the polymer, forexample, a structure having high affinity for aqueous alkali solution.

Preferred embodiments are, for example, (I) an embodiment of having, inthe polymer side chains, a functional group of formula (2) capable offorming an acid group through hydrolysis with alkali; (II) an embodimentof having, in the polymer side chains, an acid group of formula (4)having an acid dissociation constant (pKa) of from 0 to 11; and (III) anembodiment of having, in the polymer side chains, an assistant group fordissolution in aqueous alkali solution. These preferred embodiments aredescribed in detail hereinunder.

The functional group capable of forming an acid group through hydrolysiswith aqueous alkali solution (developer) having pH of at least 10 isdescribed. Preferably, the functional group is represented by formula(2), and it is desirable that the polymer has the functional group inits side chains.-Q-X¹  (2)

In formula (2), Q represents a linking group that links X¹ to thepolymer backbone chain; X¹ represents a protective group hydrolyzablewith an aqueous alkali solution having a pH of at least 10; and when thefunctional group of formula (2) gives -Q-OH after hydrolysis, the -Q-OHis an acid group having a pKa of at most 10.

Q may also be a trivalent or more multivalent linking group. In thiscase, formula (2) may be represented by the following formula (2′). nindicates an integer selected from 1 to 5.-Q

X¹)_(n)  (2′)

The linking group Q is especially such that, when the specificfunctional group has changed into -Q-OH after hydrolysis, the pKa of-Q-OH could be at most 10, more preferably from 3 to 10. Preferably, Qis a hydrocarbon-type linking group, and the hydrocarbon group for itincludes a straight chain, branched or cyclic alkyl group, and anaromatic group. From these, Q is selected so that the pKa of thespecific functional group after hydrolysis could fall within the rangeas above. In general, an electron-attractive substituent may beintroduced into such a divalent or more multivalent hydrocarbon group tothereby make the pKa of the specific functional group after hydrolysisfall within the range as above.

Preferred examples of the hydrocarbon group for Q are an aromatic groupand a cyclo group (cycloalkane group or cycloalkene group).

Not specifically defined, X¹ may be any functional group capable offunctioning as a protective group until it is removed through hydrolysiswith aqueous alkali solution having pH of at least 10.

Preferred examples of X¹ are a substituted oxy group, substituted thiogroup, and a substituted amino group.

More preferably, the specific functional group in the invention isrepresented by the following formula (3):

In formula (3), A¹ represents an aromatic group or a cyclo group(cycloalkane or cycloalkene group). Concretely, it includes an aromaticgroup, a heterocyclic group, a condensed polycyclic group or analiphatic cyclic structure having from about 4 to 50 carbon atoms.

n indicates an integer selected from 1 to 5. In view of the balancebetween the solubility in alkali of the unexposed part of the polymerand the resistance to alkali development of the exposed part thereof, nis preferably from 1 to 3.

X² represents —NR¹R², —SR³, or —OR⁴. R¹ to R⁴ each independentlyrepresent a substituent composed of at least one or more atoms selectedfrom a group consisting of a carbon atom, a hydrogen atom, an oxygenatom, a nitrogen atom, a sulfur atom and a halogen atom. For example, itincludes an optionally-substituted alkyl group, and anoptionally-substituted aryl group.

The alkyl group includes a straight chain, branched or cyclic alkylgroup having from 1 to 20 carbon atoms. Specific examples thereofinclude methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl,isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl,1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl,cyclopentyl and 2-norbornyl groups. Of the alkyl groups, a straightchain alkyl group having from 1 to 12 carbon atoms, a branched alkylgroup having from 3 to 12 carbon atoms and a cyclic alkyl group havingfrom 5 to 10 carbon atoms are preferred.

The substituent that may be introduced into the alkyl group may be amonovalent non-metallic atomic group exclusive of a hydrogen atom. Itincludes a halogen atom (e.g., fluorine, bromine, chlorine or iodine), ahydroxy group, an alkoxy group, an aryloxy group, a mercapto group, analkylthio group, an arylthio group, an alkyldithio group, an aryldithiogroup, an amino group, an N-alkylamino group, an N,N-dialkylamino group,an N-arylamino group, an N,N-diarylamino group, an N-alkyl-N-arylaminogroup, an acyloxy group, a carbamoyloxy group, an N-alkylcarbamoyloxygroup, an N-arylcarbamoyloxy group, an N,N-dialkylcarbamoyloxy group, anN,N-diarylcarbamoyloxy group, an N-alkyl-N-arylcarbamoyloxy group, analkylsulfoxy group, an arylsulfoxy group, an acylthio group, anacylamino group, an N-alkylacylamino group, an N-arylacylamino group,anureido group, an N′-alkylureido group, an N′,N′-dialkylureido group,an N′-arylureido group, an N′,N′-diarylureido group, anN′-alkyl-N′-arylureido group, an N-alkylureido group, an N-arylureidogroup, an N′-alkyl-N-alkylureido group, an N′-alkyl-N-arylureido group,an N′,N′-dialkyl-N-alkylureido group, an N′,N′-dialkyl-N-arylureidogroup, an N′-aryl-N-alkylureido group, an N′-aryl-N-arylureido group, anN′,N′-diaryl-N-alkylureido group, an N′,N′-diaryl-N-arylureido group, anN′-alkyl-N′-aryl-N-alkylureido group, an N′-alkyl-N′-aryl-N-arylureidogroup, an alkoxycarbonylamino group, an aryloxycarbonylamino group, anN-alkyl-N-alkoxycarbonylamino group, an N-alkyl-N-aryloxycarbonylaminogroup, an N-aryl-N-alkoxycarbonylamino group, anN-aryl-N-aryloxycarbonylamino group, a formyl group, an acyl group, acarboxy group and a conjugate base group thereof, an alkoxycarbonylgroup, an aryloxycarbonyl group, a carbamoyl group, an N-alkylcarbamoylgroup, an N,N-dialkylcarbamoyl group, an N-arylcarbamoyl group, anN,N-diarylcarbamoyl group, an N-alkyl-N-arylcarbamoyl group, analkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, anarylsulfonyl group, a sulfo group (—SO₃H) and a conjugate base groupthereof, an alkoxysulfonyl group, an aryloxysulfonyl group, asulfinamoyl group, an N-alkylsulfinamoyl group, anN,N-dialkylsulfinamoyl group, an N-arylsulfinamoyl group, anN,N-diarylsulfinamoyl group, an N-alkyl-N-arylsulfinamoyl group, asulfamoyl group, an N-alkylsulfamoyl group, an N,N-dialkylsulfamoylgroup, an N-arylsulfamoyl group, an N,N-diarylsulfamoyl group, anN-alkyl-N-arylsulfamoyl group, an N-acylsulfamoyl group and a conjugatebase group thereof, an N-alkylsulfonylsulfamoyl group (—SO₂NHSO₂(alkyl))and a conjugate base group thereof, an N-arylsulfonylsulfamoyl group(—SO₂NHSO₂(aryl)) and a conjugate base group thereof, anN-alkylsulfonylcarbamoyl group (—CONHSO₂(alkyl)) and a conjugate basegroup thereof, an N-arylsulfonylcarbamoyl group (—CONHSO₂ (aryl)) and aconjugate base group thereof, an alkoxysilyl group (—Si(O-alkyl)₃), anaryloxysilyl group (—Si(O-aryl)₃), a hydroxysilyl group (—Si(OH)₃) and aconjugate base group thereof, a phosphono group (—PO₃H₂) and a conjugatebase group thereof, a dialkylphosphono group (—PO₃(alkyl)₂), adiarylphosphono group (—PO₃(aryl)₂), an alkylarylphosphono group(—PO₃(alkyl) (aryl)), a monoalkylphosphono group (—PO₃H(alkyl)) and aconjugate base group thereof, a monoarylphosphono group (—PO₃H(aryl))and a conjugate base group thereof, a phosphonoxy group (—OPO₃H₂) and aconjugate base group thereof, a dialkylphosphonoxy group(—OPO₃(alkyl)₂), a diarylphosphonoxy group (—OPO₃(aryl)₂), analkylarylphosphonoxy group (—OPO₃(alkyl)(aryl)), a monoalkylphosphonoxygroup (—OPO₃H(alkyl)) and a conjugate base group thereof, amonoarylphosphonoxy group (—OPO₃H(aryl)) and a conjugate base groupthereof, a cyano group, a nitro group, a dialkylboryl group(—B(alkyl)₂), a diarylboryl group (—B(aryl)₂), an alkylarylboryl group(—B(alkyl) (aryl), a dihydroxyboryl group (—B(OH)₂) and a conjugate basegroup thereof, an alkylhydroxyboryl group (—B(alkyl)(OH)) and aconjugate base group thereof, an arylhydroxyboryl group (—B(aryl)(OH))and a conjugate base group thereof, an aryl group, an alkenyl group andan alkynyl group.

The aryl group includes a benzene ring, a condensed ring that comprises2 or 3 benzene rings, and a condensed ring that comprises a benzene ringand a 5-membered unsaturated ring. Its specific examples include phenyl,naphthyl, anthryl, phenanthryl, indenyl, acenaphthenyl and fluorenylgroups. Of those, preferred are phenyl and naphthyl groups.

The substituent that may be introduced into the aryl group includes theabove-mentioned alkyl group and those mentioned hereinabove for thesubstituent capable of being introduced into the alkyl group.

Of those for X², preferred examples of the substituted amino group of—NR¹R² include an acylamino group, an N-alkylacylamino group, anN-arylacylamino group, an ureido group, an N′-alkylureido group, anN′,N′-dialkylureido group, an N′-arylureido group, an N′,N′-diarylureidogroup, an N′-alkyl-N′-arylureido group, an N-alkylureido group, anN-arylureido group, an N′-alkyl-N-alkylureido group, anN′-alkyl-N-arylureido group, an N′,N′-dialkyl-N-alkylureido group, anN′,N′-dialkyl-N-arylureido group, an N′-aryl-N-alkylureido group, anN′-aryl-N-arylureido group, an N′,N′-diaryl-N-alkylureido group, anN′,N′-diaryl-N-arylureido group, an N′-alkyl-N′-aryl-N-alkylureidogroup, an N′-alkyl-N′-aryl-N-arylureido group, an alkoxycarbonylaminogroup, an aryloxycarbonylamino group, an N-alkyl-N-alkoxycarbonylaminogroup, an N-alkyl-N-aryloxycarbonylamino group, anN-aryl-N-alkoxycarbonylamino group and an N-aryl-N-aryloxycarbonylaminogroup. The alkyl group and the aryl group in these include thosedescribed for the alkyl group, substituted alkyl group, aryl group andsubstituted aryl group above. In an acyl group (R⁸CO—) in the acylaminogroup, N-alkylacylamino group or N-arylacylamino group described above,R⁸ has the same meaning as that described hereinabove for the alkyl,substituted alkyl, aryl, substituted aryl group. Of those, morepreferred are an N-alkylamino group, an N,N-dialkylamino group, anN-arylamino group and an acylamino group are more preferred. Specificpreferred examples of the preferred substituted amino group includemethylamino, ethylamino, diethylamino, morpholino, piperidino,pyrrolidino, phenylamino, benzoylamino and acetylamino groups.

Y represents a single bond, or —O— or —NR⁵—. R⁵ represents a hydrogenatom or a hydrocarbon atom. The hydrocarbon group for R⁵ includes analkyl group, an aryl group, an alkenyl group, and an alkynyl group.

Specific examples of the alkyl group include a straight chain, branchedor cyclic alkyl group having from 1 to 10 carbon atoms, such as methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl,isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl,1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl,cyclopentyl, 1-adamantyl and 2-norbornyl groups.

Specific examples of the aryl group include an aryl group having from 1to 10 carbon atoms, such as phenyl, naphthyl and indenyl groups; and aheteroaryl group having one hetero atom selected from nitrogen, oxygenand sulfur atoms and having from 1 to 10 carbon atoms, such as furyl,thienyl, pyrrolyl, pyridyl and quinolyl groups.

Specific examples of the alkenyl group include a straight chain,branched or cyclic alkenyl group having from 1 to 10 carbon atoms, suchas vinyl, 1-propenyl, 1-butenyl, 1-methyl-1-propenyl, 1-cyclopentenyland 1-cyclohexenyl groups.

Specific examples of the alkynyl group include those having from 1 to 10carbon atoms, such as ethynyl, 1-propynyl, 1-butynyl and 1-octynylgroups.

R⁵ may be substituted. For the substituent for it, referred to are thosementioned hereinabove for the substituent for the alkyl group for R¹ toR⁴. However, the number of the carbon atoms constituting R⁵ is from 1 to10 including the number of the carbon atoms of the substituent for it.

Preferably, Y is an oxygen atom or —NH— since the polymer production iseasy.

For introducing the specific functional group into polymer compounds,for example, employable is a method of copolymerizing a monomer havingthe specific functional group and an unsaturated bond capable ofcopolymerizing with any other comonomer in the molecule in any knownmode of polymerization. If desired, any other monomer not having thespecific functional group may be copolymerized with it. In theinvention, the structural units of such monomer in the polymer compoundobtained through such copolymerization may be referred to as “units”.

Preferred examples of the units having the specific functional group arementioned below, to which, however, the invention should not be limited.

The alkali-soluble polymer of the invention may contain one or moredifferent types of units having the specific functional group.

The alkali-soluble polymer may be a polymer comprising only the units offormula (1) and the units having the specific functional group, but ingeneral, it is combined with units of any other comonomer mentionedhereinunder. The total content of the specific functional group-havingunits in the copolymer may be suitably determined depending on thestructure of the copolymer and on the design of image-recording layersthat contain the copolymer. Preferably, it may be from 1 to 99 mol %,more preferably from 5 to 90 mol %, even more preferably from 10 to 70mol % of the total molar amount of the polymer component.

In the alkali-soluble polymer of the invention, the content of thespecific functional group, which is indispensable in the firstembodiment of the invention, is preferably from 0.05 to 10.0 mmols, morepreferably from 0.10 to 5.0 mmols, per gram of the alkali-solublepolymer.

The second embodiment of the invention is described. In the secondembodiment, an acid group of formula (4) having an acid dissociationconstant (pKa) of from 0 to 11 is introduced into the side chains of thepolymer.P—X³-(A²-H)_(m)  (4)

In formula (4), X³ represents a single bond, or a linking group selectedfrom a carboxylate group (—COO—), an amido group (—CONH—), a hydrocarbongroup and an ether group (—O— or —S—); A²-H represents a partialstructure that functions as an acid group having an acid dissociationconstant (pKa) of from 0 to 11; and m indicates an integer of from 1 to5.

The acid group having an acid dissociation constant (pKa) of from 0 to11 is described.

1. Acid Group Having an Acid Dissociation Constant (pKa) of from 0 toLess Than 5.5:

The acid group having an acid dissociation constant (pKa) of from 0 toless than 5.5 includes a sulfonic acid group, a phosphoric acid group,and a carboxyl group. Especially preferred is a carboxyl group.Concretely, for example, the carboxyl group-having structure includesacrylic acid, methacrylic acid, itaconic acid, crotonic acid,isocrotonic acid, maleic acid and p-carboxystyrene. More preferred areacrylic acid, methacrylic acid and p-carboxystyrene. One or more ofthese may be employed herein.

2. Acid Group Having an Acid Dissociation Constant (pKa) of from 5.5 to11:

The acid group having an acid dissociation constant (pKa) of from 5.5 to11 that may be in the alkali-soluble polymer of the invention isdescribed. Its pKa is preferably from 7 to 11, more preferably from 8 to11.

Concretely, for example, the acid group includes a phenol group(pKa=9.99), a 2-methoxyphenol group (pKa=9.99), a 2-chlorophenol group(pKa=8.55), a methyl 2-hydroxybenzoate group (pKa=9.87), a4-methylphenol group (pKa=10.28), a 1,3-benzenediol group (pKa=9.20), a1-naphthol group (pKa=9.30), a 1,2-benzenediol group (pKa=9.45), abenzenesulfonamido group (pKa=10.00), anN-acetylphenylbenzenesulfonamido group (pKa=6.94), a4-aminobenzenesulfonamido group (pKa=10.58), anN-phenyl-4-aminobenzenesulfonamido group (pKa=6.30), anN-(4-acetylphenyl)-4-aminobenzenesulfonamido group (pKa=7.61), and anethyl acetylacetate group (pKa=10.68). Of those, more preferred arephenol groups optionally substituted on the aromatic group thereof, andbenzenesulfonamido groups optionally substituted on the aromatic groupthereof.

The data of the acid dissociation constant pKa of the above-mentionedspecific examples are those described in E. P. Serjeant et al.,Ionization Constants of Organic Acids in Aqueous Solution, and in JohnA. Dean, Lange's Handbook of Chemistry.

The structural unit that has the specific acid group as above ispreferably represented by the following formula (5):

In formula (5), X represents O, S or —NR⁴—; Y represents a divalentorganic group; A represents a specific acid group; R¹, R², R³ and R⁴each independently represent a hydrogen atom, a halogen atom, amonovalent organic group, a cyano group or a nitro group.

In formula (5), the monovalent organic group for R¹, R², R³ and R⁴includes, for example, a straight chain, branched or cyclic alkyl group,an aromatic group, an alkoxy group, an acyl group, an aralkyl group, analkoxycarbonyl group, and an aryloxy group.

The monovalent organic group may be further substituted. The substituentthat may be introduced into it includes, for example, an alkyl group, anaryl group, an alkoxy group, an acyloxy group, a halogen atom, ahydroxyl group, an amino group, a cyano group, and a nitro group.

In formula (5), the divalent organic group for Y includes, for example,an alkylene group, a phenylene group, and a naphthylene group.

The divalent organic group may be further substituted. The substituentthat may be introduced into it includes, for example, an alkyl group, anaryl group, an alkoxy group, an acyloxy group, a halogen atom, ahydroxyl group, an amino group, a cyano group, and a nitro group.

For the structural unit that has the specific acid group, also preferredare those of the following formulae (6) to (11):

In formula (6), R represents a hydrogen atom or an alkyl group; Xrepresents a divalent linking group; and Y represents anoptionally-substituted divalent aromatic group.

In formula (6), the divalent linking group for X includes, for example,an optionally-substituted alkylene or phenylene group. Theoptionally-substituted divalent aromatic group for Y includes, forexample, an optionally-substituted phenylene or naphthylene group.

In formula (7), R¹ and R² each independently represent a hydrogen atom,an alkyl group, or a carboxyl group; R³ represents a hydrogen atom, ahalogen atom, or an alkyl group; R⁴ represents a hydrogen atom, an alkylgroup, a phenyl group, or an aralkyl group; X represents a divalentorganic group that links the nitrogen atom to the carbon atom of thearomatic ring in the formula; n indicates 0 or 1; Y represents anoptionally-substituted phenylene group, or an optionally-substitutednaphthylene group.

Formula (7) is described in detail.

In the structural unit of formula (7), Y is an optionally-substitutedphenylene group or an optionally-substituted naphthylene group. The typeof the substituent for the group does not almost have any significantinfluence on the properties of the polymerizable composition of theinvention. Therefore, the group may have any type of substituent.Specific examples of the substituent include an alkyl group, an alkoxygroup, a halogen atom, an acyl group, a hydroxyl group, a carboxylgroup, a sulfonic acid group, a cyano group, and a nitro group.

In formula (8), R¹ represents a hydrogen atom, a halogen atom, a cyanogroup, or an alkyl group; R² and R³ each independently represent ahydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or anaryl group; X represents an atomic group necessary for completing amonocyclic or polycyclic, carbon-cyclic aromatic ring system; nindicates 1, 2 or 3.

In the structural unit of formula (8), preferably, R¹ is a hydrogenatom, a halogen atom, a cyano group, or an alkyl group having from 1 to6 carbon atoms; R² and R³ are independently a hydrogen atom, or an alkylgroup having from 1 to 4 carbon atoms; R⁴, R⁵ and R⁶ are independently ahydrogen atom, an alkyl group having from 1 to 4 carbon atoms, or ahalogen atom; X is carbon atoms necessary for completing a benzene ringor a naphthalene ring; and n is 1.

In the structural unit of formula (8), more preferably, R¹ is a hydrogenatom or a methyl group; R², R³ and R⁴ are hydrogen atoms; R⁵ is ahydrogen atom, an alkyl group having from 1 to 4 carbon atoms, or ahalogen atom; R⁶ is a hydrogen atom, an alkyl group having from 1 to 4carbon atoms, an aryl group, or a halogen atom; X is carbon atomsnecessary for completing a benzene ring or a naphthalene ring; and n is1.

When R¹ is an alkyl group in formula (8), it preferably has from 1 to 6carbon atoms, more preferably 1 or 2 carbon atoms. Even more preferably,R¹ is a hydrogen atom or a methyl group.

In formula (8), at least one of R² and R³ is preferably a hydrogen atom.When R² and R³ are an alkyl group, the group preferably has from 1 to 6carbon atoms, more preferably from 1 to 3 carbon atoms.

In formula (8), R⁴ is preferably a hydrogen atom. R⁵ is preferably analkyl group having from 1 to 4 carbon atoms, more preferably a methylgroup. R⁶ is preferably an alkyl group having from 1 to 4 carbon atoms,or an aryl group.

In general, the alkyl group as referred to herein is meant to indicate acyclic or open-chain, branched or unbranched, saturated or unsaturatedgroup that may be substituted with a halogen atom or a hydroxyl groupand may contain an ether group or a ketone group. Preferably, it is anunbranched alkyl group having from 1 to 4 carbon atoms. The aryl groupmay be a monocyclic or polycyclic, heterocyclic or carbon-cyclicaromatic ring system that may be substituted with an aryl group, analkoxy group, a hydroxy group or a halogen atom.

The position of the substituents on the ring X is not specificallydefined, and it depends on only the easiness in producing the compounds.

The carbon-cyclic aromatic ring system X may be monocyclic orpolycyclic. The carbon-cyclic ring system is typically a benzene ornaphthalene system.

The halogen atom in formula (8) is preferably a chlorine, bromine oriodine atom, more preferably a chlorine atom.

In formulae (9) and (10), X¹ and X² each independently represent —O— or—NR⁷—; R¹ and R⁴ each independently represent —H or —CH₃; R² and R⁵ eachindependently represent an optionally-substituted alkylene,cycloalkylene, arylene or aralkylene group having from 1 to 12 carbonatoms; R³ represents —H, or an optionally-substituted alkyl, cycloalkyl,aryl or aralkyl group having from 1 to 12 carbon atoms; R⁶ represents anoptionally-substituted alkyl, cycloalkyl, aryl or aralkyl group havingfrom 1 to 12 carbon atoms; R⁷ represents a hydrogen atom, or anoptionally-substituted alkyl, cycloalkyl, aryl or aralkyl group havingfrom 1 to 12 carbon atoms.

In formula (11), A¹ represents a hydrogen atom, a halogen atom, or analkyl group having from 1 to 4 carbon atoms; B¹ represents a phenylenegroup, or a substituted phenylene group; B² represents an optionallysubstituted alkylene group having from 2 to 6 carbon atoms, or anoptionally-substituted phenylene group; B³ represents a divalent organicgroup; X¹ and X² each independently represent —CO—, or —SO₂—; Yrepresents —CO—R¹— or —SO₂—R¹; R¹ represents an alkyl group, asubstituted alkyl group, an aromatic group, or a substituted aromaticgroup; and m and j are 0 or 1.

Specific examples (B-1 to B-6, C-1 to C-15, D-1 to D-6, E-1 to E-15, F-1to F-13, G-1 to G-3, H-1 to H-2, J-1 to J-2) of the comonomers usablefor the structural units of formulae (5) to (11) are mentioned below, towhich, however, the invention should not be limited. These comonomersare produced according to the methods described in JP-A 7-333839, JP-A8-339080, JP-B 52-28401, JP-A 4-212961, JP-A 2-866, and JP-A 8-286369.

Either singly or as combined, one or more different types of thespecific acid group-having structural units mentioned above may be inthe specific binder polymer.

In the alkali-soluble polymer of the second embodiment of the invention,the content of the acid group having an acid dissociation constant (pKa)of from 0 to 11 is preferably from 0.01 to 10.0 mmols, more preferablyfrom 0.05 to 7.0 mmols per gram of the alkali-soluble polymer.

The third embodiment of the invention is described. In the thirdembodiment, an assistant group for dissolution in aqueous alkalisolution is introduced into the side chains of the polymer. Theassistant group for dissolution in aqueous alkali solution is not anacid group (alkali-soluble group) by itself but substantiallyparticipates in improving the solubility in alkali of the polymer. Forexample, it has a partial structure having high affinity for aqueousalkali solution. Concretely, its preferred examples include alcohols,polyol derivatives, saccharide derivatives, amide derivatives, imidederivatives, and guanidine derivatives.

The alkali-soluble polymer of the invention must have, in the sidechains thereof, a functional group that has a carboxyl group of—CO-A-R²—(COOH)n. For introducing the functional group into the sidechains of alkali-soluble polymer, for example, the units having thespecific functional group as above may be combined with the units havingthe structure of formula (1) mentioned below. Apart from this,radical-polymerizable group-having units or any other comonomers may becombined with them, as in the preferred embodiments mentioned below.

The content of the carboxyl group of formula (1) in the alkali-solublepolymer is preferably from 0.1 to 10.0 mmols, more preferably from 0.3to 5.0 mmols, most preferably from 0.5 to 4.0 mmols per gram of thealkali-soluble polymer. One or more different types of the units offormula (1) may be in the alkali-soluble polymer.

In formula (1), R¹ represents a hydrogen atom or a methyl group, and ispreferably a methyl group.

R² represents an (n+1)-valent linking group. For example, this is an(n+1)-valent organic linking group that comprises one or more atomsselected from a group consisting of a hydrogen atom, an oxygen atom, anitrogen atom, a sulfur atom and a halogen atom and contains an estergroup of —O(C═O)—.

Preferably, the linking group for R² has from 5 to 20 carbon atoms andhas a chain structure, and contains an ester bond in the structure.

The substituent that may be introduced into the linking group for R² maybe a monovalent non-metallic atomic group exclusive of a hydrogen atom.It includes a halogen atom (e.g., fluorine, bromine, chlorine oriodine), a hydroxy group, an alkoxy group, an aryloxy group, a mercaptogroup, an alkylthio group, an arylthio group, an alkyldithio group, anaryldithio group, an amino group, an N-alkylamino group, anN,N-dialkylamino group, an N-arylamino group, an N,N-diarylamino group,an N-alkyl-N-arylamino group, an acyloxy group, a carbamoyloxy group, anN-alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, anN,N-dialkylcarbamoyloxy group, an N,N-diarylcarbamoyloxy group, anN-alkyl-N-arylcarbamoyloxy group, an alkylsulfoxy group, an arylsulfoxygroup, an acylthio group, an acylamino group, an N-alkylacylamino group,an N-arylacylamino group, anureido group, an N′-alkylureido group, anN′,N′-dialkylureido group, an N′-arylureido group, an N′,N′-diarylureidogroup, an N′-alkyl-N′-arylureido group, an N-alkylureido group, anN-arylureido group, an N′-alkyl-N-alkylureido group, anN′-alkyl-N-arylureido group, an N′,N′-dialkyl-N-alkylureido group, anN′,N′-dialkyl-N-arylureido group, an N′-aryl-N-alkylureido group, anN′-aryl-N-arylureido group, an N′,N′-diaryl-N-alkylureido group, anN′,N′-diaryl-N-arylureido group, an N′-alkyl-N′-aryl-N-alkylureidogroup, an N′-alkyl-N′-aryl-N-arylureido group, an alkoxycarbonylaminogroup, an aryloxycarbonylamino group, an N-alkyl-N-alkoxycarbonylaminogroup, an N-alkyl-N-aryloxycarbonylamino group, anN-aryl-N-alkoxycarbonylamino group, an N-aryl-N-aryloxycarbonylaminogroup, a formyl group, an acyl group, a carboxy group and a conjugatebase group thereof, an alkoxycarbonyl group, an aryloxycarbonyl group, acarbamoyl group, an N-alkylcarbamoyl group, an N,N-dialkylcarbamoylgroup, an N-arylcarbamoyl group, an N,N-diarylcarbamoyl group, anN-alkyl-N-arylcarbamoyl group, an alkylsulfinyl group, an arylsulfinylgroup, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group(—SO₃H) and a conjugate base group thereof, an alkoxysulfonyl group, anaryloxysulfonyl group, a sulfinamoyl group, an N-alkylsulfinamoyl group,an N,N-dialkylsulfinamoyl group, an N-arylsulfinamoyl group, anN,N-diarylsulfinamoyl group, an N-alkyl-N-arylsulfinamoyl group, asulfamoyl group, an N-alkylsulfamoyl group, an N,N-dialkylsulfamoylgroup, an N-arylsulfamoyl group, an N,N-diarylsulfamoyl group, anN-alkyl-N-arylsulfamoyl group, an N-acylsulfamoyl group and a conjugatebase group thereof, an N-alkylsulfonylsulfamoyl group (—SO₂NHSO₂(alkyl))and a conjugate base group thereof, an N-arylsulfonylsulfamoyl group(—SO₂NHSO₂(aryl)) and a conjugate base group thereof, anN-alkylsulfonylcarbamoyl group (—CONHSO₂(alkyl)) and a conjugate basegroup thereof, an N-arylsulfonylcarbamoyl group (—CONHSO₂ (aryl)) and aconjugate base group thereof, an alkoxysilyl group (—Si(O-alkyl)₃), anaryloxysilyl group (—Si(O-aryl)₃), a hydroxysilyl group (—Si (OH)₃) anda conjugate base group thereof, a phosphono group (—PO₃H₂) and aconjugate base group thereof, a dialkylphosphono group (—PO₃(alkyl)₂), adiarylphosphono group (—PO₃(aryl)₂), an alkylarylphosphono group(—PO₃(alkyl)(aryl)), a monoalkylphosphono group (—PO₃H(alkyl)) and aconjugate base group thereof, a monoarylphosphono group (—PO₃H(aryl))and a conjugate base group thereof, a phosphonoxy group (—OPO₃H₂) and aconjugate base group thereof, a dialkylphosphonoxy group(—OPO₃(alkyl)₂), a diarylphosphonoxy group (—OPO₃(aryl)₂), analkylarylphosphonoxy group (—OPO₃ (alkyl)(aryl)), a monoalkylphosphonoxygroup (—OPO₃H (alkyl)) and a conjugate base group thereof, amonoarylphosphonoxy group (—OPO₃H(aryl)) and a conjugate base groupthereof, a cyano group, a nitro group, a dialkylboryl group(—B(alkyl)₂), a diarylboryl group (—B(aryl)₂), an alkylarylboryl group(—B(alkyl)(aryl), a dihydroxyboryl group (—B(OH)₂) and a conjugate basegroup thereof, an alkylhydroxyboryl group (—B(alkyl)(OH)) and aconjugate base group thereof, an arylhydroxyboryl group (—B(aryl)(OH))and a conjugate base group thereof, an aryl group, an alkenyl group andan alkynyl group.

In particular, when the alkali-soluble polymer of the invention is usedas a component of the recording layer of lithographic printing plateprecursors, then substituents having a hydrogen-bondable hydrogen atomand especially acidic substituents having a smaller acid dissociationconstant (pKa) than carboxylic acids are unfavorable, though dependingon the design of the recording layer, since they tend to lower theprinting durability of the printing plates produced. On the other hand,hydrophobic substituents such as a halogen atom, a hydrocarbon group(alkyl group, aryl group, alkenyl group, alkynyl group), an alkoxy groupand an aryloxy group are more preferred as they tend to improve theprinting durability of the printing plate produced. In particular, whenthe linking group is a monocyclic aliphatic hydrocarbon group having a6-membered or smaller cyclic structure such as cyclopentane orcyclohexane, then the hydrocarbon group preferably has such hydrophobicsubstituent. If possible, these substituents may bond to each other orto the hydrocarbon group to form a ring. The substituents may be furthersubstituted.

R³ in NR³— for A in formula (1) is a hydrogen atom, or a monovalenthydrocarbon group having from 1 to 10 carbon atoms. The monovalenthydrocarbon group having from 1 to 10 carbon atoms for R³ includes analkyl group, an aryl group, an alkenyl group, and an alkynyl group.

Specific examples of the alkyl group include a straight chain, branchedor cyclic alkyl group having from 1 to 10 carbon atoms, such as methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl,isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl,1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclopentyl,cyclohexyl, 1-adamantyl and 2-norbornyl groups.

Specific examples of the aryl group include an aryl group having from 1to 10 carbon atoms, such as phenyl, naphthyl and indenyl groups; and aheteroaryl group having one hetero atom selected from nitrogen, oxygenand sulfur atoms and having from 1 to 10 carbon atoms, such as furyl,thienyl, pyrrolyl, pyridyl and quinolyl groups.

Specific examples of the alkenyl group include a straight chain,branched or cyclic alkenyl group having from 1 to 10 carbon atoms, suchas vinyl, 1-propenyl, 1-butenyl, 1-methyl-1-propenyl, 1-cyclopentenyland 1-cyclohexenyl groups.

Specific examples of the alkynyl group include those having from 1 to 10carbon atoms, such as ethynyl, 1-propynyl, 1-butynyl and 1-octynylgroups.

For the substituent which R³ may have, referred to are those mentionedhereinabove for the substituent for R². However, the number of thecarbon atoms constituting R³ is from 1 to 10 including the number of thecarbon atoms of the substituent for it.

Preferably, A in formula (1) is an oxygen atom or —NH— since the polymerproduction is easy.

In formula (1), n indicated an integer of from 1 to 5, and is preferably1 in view of the printing durability of the printing plates produced.

Preferred examples of the units of formula (1) are mentioned below, towhich, however, the invention should not be limited.

Preferably, the alkali-soluble polymer of the invention has, in the sidechains thereof, an ethylenic unsaturated double bond (hereinafterreferred to as “radical-polymerizable group”) For introducing such aradical-polymerizable group into the side chains of the alkali-solublepolymer of the invention, for example, employable is a method ofcombining units having a radical-polymerizable group of any of thefollowing formulae (A) to (E) in addition to the specific functionalgroup-having units mentioned above. The content of theradical-polymerizable group in the alkali-soluble polymer(radical-polymerizable unsaturated double bond content determinedthrough iodine titration) is preferably from 0.1 to 10.0 mmols, morepreferably from 1.0 to 8.0 mmols, most preferably from 1.5 to 7.0 mmolsper gram of the alkali-soluble polymer. One or more different types ofthese units may be in the alkali-soluble polymer.

Formulae (A) to (E) are described. In formulae (A) to (C), R⁴ to R¹⁴each independently represent a hydrogen atom, or a monovalentsubstituent; X and Y each independently represent an oxygen atom, asulfur atom, or N—R¹⁵; Z represents an oxygen atom, a sulfur atom,—N—R¹⁵, or a phenylene group; R¹⁵ represents a hydrogen atom, or amonovalent organic group.

In formula (A), R⁴ to R⁶ are independently a hydrogen atom, or amonovalent substituent. R⁴ may be a hydrogen atom, or an organic groupsuch as an optionally-substituted alkyl group. Concretely, R⁴ ispreferably a hydrogen atom, a methyl group, an ethyl group, an alkoxygroup, or a methyl ester group. R⁵ and R⁶ are independently a hydrogenatom, a halogen atom, an amino group, a dialkylamino group, a carboxylgroup, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyanogroup, an optionally-substituted alkyl group, an optionally-substitutedaryl group, an optionally-substituted alkoxy group, anoptionally-substituted aryloxy group, an optionally-substitutedalkylamino group, an optionally-substituted arylamino group, anoptionally-substituted alkylsulfonyl group, or an optionally-substitutedarylsulfonyl group. Preferably, R⁵ and R⁶ are independently a hydrogenatom, a carboxyl group, an alkoxycarbonyl group, anoptionally-substituted alkyl group, or an optionally-substituted arylgroup.

The substituent that may be introduced into these groups includes amethoxycarbonyl group, an ethoxycarbonyl group, an isopropoxycarbonylgroup, a methyl group, an ethyl group, and a phenyl group.

X is an oxygen atom, a sulfur atom, or —N—R¹⁵. R¹⁵ may be anoptionally-substituted alkyl group.

In formula (B), R⁷ to R¹¹ are independently a hydrogen atom, or amonovalent substituent. For example, R⁷ to R¹¹ are independently ahydrogen atom, a halogen atom, an amino group, a dialkylamino group, acarboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, acyano group, an optionally-substituted alkyl group, anoptionally-substituted aryl group, an optionally-substituted alkoxygroup, an optionally-substituted aryloxy group, anoptionally-substituted alkylamino group, an optionally-substitutedarylamino group, an optionally-substituted alkylsulfonyl group, or anoptionally-substituted arylsulfonyl group. Preferably, R⁷ to R¹¹ areindependently a hydrogen atom, a carboxyl group, an alkoxycarbonylgroup, an optionally-substituted alkyl group, or anoptionally-substituted aryl group.

For the substituent that may be introduced into these groups, referredto are those mentioned hereinabove for the groups in formula (A).

Y is an oxygen atom, a sulfur atom, or —N—R¹⁵. R¹⁵ may be the same as informula (A).

In formula (C), R¹² to R¹⁴ are independently a hydrogen atom, or amonovalent substituent. Concretely, for example, R¹² to R¹⁴ areindependently a hydrogen atom, a halogen atom, an amino group, adialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfogroup, a nitro group, a cyano group, an optionally-substituted alkylgroup, an optionally-substituted aryl group, an optionally-substitutedalkoxy group, an optionally-substituted aryloxy group, anoptionally-substituted alkylamino group, an optionally-substitutedarylamino group, an optionally-substituted alkylsulfonyl group, or anoptionally-substituted arylsulfonyl group. Preferably, R¹² to R¹⁴ areindependently a hydrogen atom, a carboxyl group, an alkoxycarbonylgroup, an optionally-substituted alkyl group, or anoptionally-substituted aryl group.

For the substituent that may be introduced into these groups, referredto are those mentioned hereinabove for the groups in formula (A).

Z is an oxygen atom, a sulfur atom, —N—R¹⁵, or a phenylene group. R¹⁵may be the same as in formula (A).

Preferred examples of the units having such a radical-polymerizablegroup of formulae (A) to (C) are mentioned below, to which, however, theinvention should not be limited.

The polymer for the invention that has a radical-polymerizable group offormula (A) may be produced according to at least any one of thefollowing production methods <1> and <2>.

Production Method <1>:

At least one radical-polymerizable compound of the following formula (a)is polymerized to give a polymer compound, and this is deprotonated witha base to thereby remove Z¹ to give the intended polymer compound.

In formula (a), R⁴ to R⁶ have the same meanings as R⁴ to R⁶ in formula(A); Z1 represents an anionic removable group; Q represents an oxygenatom, —NH—, or —NR¹⁷—; R¹⁷ represents an optionally-substituted alkylgroup; R¹⁶ represents a hydrogen atom, or an optionally-substitutedalkyl group, preferably a hydrogen atom, a methyl group, a methylalkoxygroup, or a methyl ester group; A represents a divalent organic linkinggroup.

Examples of the radical-polymerizable compound of formula (a) arementioned below, to which, however, the invention should not be limited.

These radical-polymerizable compounds of formula (a) are available ascommercial products, or can be readily produced according to theproduction method shown in Production Examples mentioned below.

At least one radical-polymerizable compound of formula (a) ispolymerized optionally along with any other radical-polymerizablecompound in a mode of ordinary radical polymerization to give a polymercompound, then a predetermined amount of a base is dropwise added to andreacted with the polymer solution with cooling or heating, and ifdesired, this is neutralized with acid whereby a group of formula (A)can be introduced into the polymer. For producing the polymer compound,employable is any known suspension polymerization or solutionpolymerization method.

The base for use herein may be any of an inorganic compound (inorganicbase) or an organic compound (organic base). Preferred examples of theinorganic base are sodium hydroxide, potassium hydroxide, sodiumcarbonate, sodium hydrogencarbonate, potassium carbonate, and potassiumhydrogencarbonate. Preferred examples of the organic base are metalalkoxides such as sodium methoxide, sodium ethoxide, potassiumt-butoxide; and organic amine compounds such as triethylamine, pyridine,diisopropylethylamine.

Production Method <2>:

At least one functional group-having radical-polymerizable compound ispolymerized to give a stem polymer compound (polymer compound to formbackbone chain), and this is reacted with a compound having a structureof the following formula (b) at the functional group in the side chainsof the stem polymer compound to give the intended polymer compound.

R⁴ to R⁶ in formula (b) have the same meanings as R⁴ to R⁶ in formula(A).

Examples of the functional group in the functional group-havingradical-polymerizable compound to be used for producing the stem polymercompound according to the production method <2> include a hydroxylgroup, a carboxyl group, a carboxylic acid halide group, a carboxylicacid anhydride group, an amino group, a halogenoalkyl group, anisocyanate group, and an epoxy group. Specific examples of theradical-polymerizable group having such a functional group include2-hydroxyethyl acrylate, 2-hydroxyethylmethacrylate, 4-hydroxybutylacrylate, 4-hydroxybutyl methacrylate, acrylic acid, methacrylic acid,acrylic acid chloride, methacrylic acid chloride, methacrylic anhydride,N,N-dimethyl-2-aminoethyl methacrylate, 2-chloroethyl methacrylate,2-isocyanatoethyl methacrylate, glycidyl acrylate, and glycidylmethacrylate.

At least one radical-polymerizable compound having such a functionalgroup is polymerized, and optionally copolymerized with any otherradical-polymerizable compound to give a stem polymer compound, and thenthis may be reacted with a compound having the group of formula (b) togive the desired polymer compound.

Examples of the compounds having the group of formula (b) may be thesame as those mentioned hereinabove for the examples of the functionalgroup-having radical-polymerizable group.

The polymer for the invention that has a radical-polymerizable group offormula (B) may be produced according to at least any one of thefollowing production methods <3> and <4>.

Production Method <3>:

At least one radical-polymerizable compound having an unsaturated groupof formula (B) and an ethylenic unsaturated group that is moreaddition-polymerizable than the unsaturated group is polymerizedoptionally along with any other radical-polymerizable to give a polymercompound. In this method, the compound used has multiple ethylenicunsaturated groups that differ in point of the addition-polymerizabilitythereof in one molecule, for example, allyl methacrylate is used.

Examples of the radical-polymerizable compound having an unsaturatedgroup of formula (B) and an ethylenic unsaturated group that is moreaddition-polymerizable than the unsaturated group of formula (B) includeallyl acrylate, allyl methacrylate, 2-allyloxyethyl acrylate,2-allyloxyethyl methacrylate, propargyl acrylate, propargylmethacrylate, N-allyl acrylate, N-allyl methacrylate, N,N-diallylacrylate, N,N-diallylmethacrylamide, allylacrylamide, andallylmethacrylamide.

Production Method <4>:

At least one functional group-having radical-polymerizable compound ispolymerized to give a polymer compound, and this is reacted with acompound having a structure of the following formula (c) at thefunctional group in the side chains of the polymer compound to therebyintroduce a group of formula (B) into the polymer compound.

R⁷ to R¹¹ in formula (c) have the same meanings as R⁷ to R¹¹ in formula(B).

Examples of the functional group-having radical-polymerizable compoundfor use in the production method <4> may be the same as those of thefunctional group-having radical-polymerizable compound used in theproduction method <2>.

Examples of the compound having the structure of formula (c) includeallyl alcohol, allylamine, diallylamine, 2-allyloxyethyl alcohol,2-chloro-1-butene, and allyl isocyanate.

The polymer for the invention that has a radical-polymerizable group offormula (C) may be produced according to at least any one of thefollowing production methods <5> and <6>.

Production Method <5>:

At least one radical-polymerizable compound having an unsaturated groupof formula (C) and an ethylenic unsaturated group that is moreaddition-polymerizable than the unsaturated group is polymerizedoptionally along with any other radical-polymerizable to give a polymercompound.

Examples of the radical-polymerizable compound having an unsaturatedgroup of formula (C) and an ethylenic unsaturated group that is moreaddition-polymerizable than the unsaturated group of formula (C) includevinyl acrylate, vinyl methacrylate, 2-phenylvinyl acrylate,2-phenylvinyl methacrylate, 1-propenyl acrylate, 1-propenylmethacrylate, vinylacrylamide, and vinylmethacrylamide.

Production Method <6>:

At least one functional group-having radical-polymerizable compound ispolymerized to give a polymer compound, and this is reacted with acompound having a structure of the following formula (d) at thefunctional group in the side chains of the polymer compound to therebyintroduce a group of formula (C) into the polymer compound.

R¹² to R¹⁴ in formula (d) have the same meanings as R¹² to R¹⁴ informula (C).

Examples of the functional group-having radical-polymerizable compoundfor use in the production method <6> may be the same as those of thefunctional group-having radical-polymerizable compound used in theproduction method <2>.

Examples of the compound having the structure of formula (d) include2-hydroxyethyl monovinyl ether, 4-hydroxybutyl monovinyl ether,diethylene glycol monovinyl ether, and 4-chloromethylstyrene.

Production methods <1> to <6> for the polymer for the invention that hasa radical-polymerizable group of formulae (A) to (C) are describedabove. When the specific binder polymer of the invention is producedaccording to these production methods <1> to <6>, theradical-polymerizable compound in these methods is copolymerized withunits of formula (1) in a predetermined ratio.

Formulae (D) and (E) are described.

In formula (D), R¹⁶ represents a hydrogen atom or a methyl group; R¹⁷represents a substitutable atom or atomic group; and k indicates aninteger of from 0 to 4. The radical-polymerizable group of formula (D)bonds to the polymer backbone via a single bond or via a linking groupof an atom or an atomic group, and its bonding mode is not specificallydefined.

In formula (E), R¹⁸ represents a hydrogen atom or a methyl group; R¹⁹represents a substitutable atom or atomic group; m indicates an integerof from 0 to 4; and A represents an anion. The pyridinium ring of thetype may be in the form of benzopyridinium having a benzene ringcondensed as a substituent thereto. This includes a quinolinium groupand an isoquinolinium group. The radical-polymerizable group of formula(E) bonds to the polymer backbone via a single bond or via a linkinggroup of an atom or an atomic group, and its bonding mode is notspecifically defined.

Preferred examples of the units (repetitive units) having theradical-polymerizable group of formulae (D) or (E) are mentioned below,to which, however, the invention should not be limited.

Of the radical-polymerizable groups of formulae (A) to (E) mentionedabove, preferred are those of formulae (A) and (B). More preferred arethe radical-polymerizable groups of formula (4); and most preferred arethose where R⁴ is a hydrogen atom or a methyl group, and X is an oxygenatom or a nitrogen atom.

Apart from the indispensable component thereof, the carboxylgroup-having units, and the preferred radical-polymerizable group-havingunits thereof mentioned above, the alkali-soluble polymer of theinvention may be further copolymerized with any other component such asthose mentioned hereinunder. Not specifically defined, any knownradical-polymerizable monomers may be used for the comonomer component.Concretely mentioned are monomers described in Polymer DataHandbook—Primary Edition—(edited by the Polymer Society of Japan,Baifukan, 1986). One or more such comonomers may be used herein eithersingly or as combined.

Above all, especially preferred comonomers are radical-polymerizablegroup-having monomers mentioned below.

For example, they are radical-polymerizable compounds selected fromacrylates, methacrylates, N,N-disubstituted acrylamides,N,N-disubstituted methacrylamides, styrenes, acrylonitriles, andmethacrylonitriles.

Concretely, they include acrylates such as alkyl acrylates (in which thealkyl group preferably has from 1 to 20 carbon atoms) (e.g., methylacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amylacrylate, ethylhexyl acrylate, octyl acrylate, t-octyl acrylate,chloroethyl acrylate, 2,2-dimethylhydroxypropyl acrylate,5-hydroxypentyl acrylate, trimethylolpropane monoacrylate,pentaerythritol monoacrylate, glycidyl acrylate, benzyl acrylate,methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate),aryl acrylates (e.g., phenyl acrylate), alkyl methacrylates (in whichthe alkyl group preferably has from 1 to 20 carbon atoms) (e.g., methylmethacrylate, ethyl methacrylate, propyl methacrylate, isopropylmethacrylate, amyl methacrylate, hexylmethacrylate, cyclohexylmethacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octylmethacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate,2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropanemonomethacrylate, pentaerythritol monomethacrylate, glycidylmethacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate),aryl methacrylates (e.g., phenyl methacrylate, cresyl methacrylate,naphthyl methacrylate), styrenes such as styrene, alkylstyrenes (e.g.,methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene,diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene,cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene,trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene),alkoxystyrenes (e.g., methoxystyrene, 4-methoxy-3-methylstyrene,dimethoxystyrene), halogenostyrenes (e.g., chlorostyrene,dichlorostyrene, trichlorostyrene, tetrachlorostyrene,pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene,fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene,4-fluoro-3-trifluoromethylstyrene), acrylonitrile, andmethacrylonitrile.

Of those radical-polymerizable compounds, preferred are acrylates,methacrylates and styrenes.

One or more of these radical-polymerizable compounds may be used hereineither singly or as combined.

Specific examples of the alkali-soluble polymer of the invention aredescribed below. (i-1) to (i-46) have the above-mentionedradical-polymerizable group, and (ii-1) to (ii-5) do not have it.However, the invention should not be limited to these.

For example, when the alkali-soluble polymer of the invention is used ina component of a recording layer of lithographic printing plateprecursors, the molecular weight of the polymer may be suitablydetermined from the viewpoint of the image-formability of the precursorsand the printing durability of the printing plates from the precursors.In general, when the molecular weight of the polymer increases, then theprinting durability will be good but the image-formability may be poor.On the contrary, when the molecular weight of the polymer is low, thenthe image-formability will be good but the printing durability may bepoor. Preferably, the molecular weight of the alkali-soluble polymer isfrom 400 to 6,000,000, more preferably from 900 to 600,000 in terms ofthe weight-average molecular weight thereof.

[Polymerizable Composition]

The polymerizable composition of the invention comprises, as theindispensable components thereof, (A) the alkali-soluble polymer of theinvention that has the specific structure and the specific physicalproperties as mentioned above, (B) an ethylenic unsaturated bond-havingcompound and (C) a compound of generating a radical by light or heat,preferably containing an optional component (D) sensitizing dye.

In the polymerizable composition, the compound (C) of generating aradical by light or heat is decomposed to form a radical, and triggeredby the thus-formed radical, the ethylenic unsaturated bond-havingcompound (B) undergoes polymerization. The polymerizable composition ofthe invention is usable in various applications that utilize themechanism thereof. For example, it is suitable to image-recording layersof negative image-recording materials (e.g., lithographic printing plateprecursors) and to high-sensitivity holographic materials, for example,those of forming holograms on the basis of the refractivity change withpolymerization thereof. In addition, it is usable in producingelectronic materials such as photoresists. Of those, the polymerizablecomposition of the invention is, when further containing a sensitizingdye, especially favorable to image recording layers of negativelithographic printing plate precursors that accept direct imageformation thereon through scanning exposure.

When the polymerizable composition of the invention is applied tonegative image-forming materials, it is desirable that theimage-recording layer contains, as the sensitizing dye (D), anIR-absorbent so that the materials could be especially favorable forplate-making in a mode of direct image formation thereon with laserlight having a wavelength of from 300 to 1,200 nm.

The components of the polymerizable composition of the invention aredescribed in detail hereinunder. [(A) Alkali-soluble polymer containinga unit structure having a carboxyl group of formula (1) at a side chainof the unit structure, and forming no deposition when dissolved in anaqueous alkali solution having a pH of at least 10 and left at roomtemperature for 60 days]

The component (A) of the polymerizable composition of the invention isat least one alkali-soluble polymer of the invention having the specificphysical properties mentioned above (hereinafter referred to as“specific alkali-soluble polymer”) and selected from the above-mentionedpreferred embodiments of the alkali-soluble polymer.

Apart from the specific alkali-soluble polymer, the polymerizablecomposition of the invention may contain one or more other binderpolymers. The amount of the additional binder polymer that may becombined with the specific alkali-soluble polymer in the polymerizablecomposition of the invention may be from 1 to 60% by weight, preferablyfrom 1 to 40% by weight, more preferably from 1 to 20% by weight of thetotal weight of all the binder polymer component in the composition.

Any known ones may be used for the additional binder polymer with nolimitation. Concretely for it, preferred are acrylic-based binders andurethane binders well used in the art.

In the polymerizable composition of the invention, the total amount ofall the binder polymer (specific alkali-soluble polymer alone ormixture) may be suitably determined. For example, when the polymerizablecomposition is used in the recording layer of image-recording materials,then the total amount of all the binder polymer in the composition maybe generally from 10 to 90% by weight, preferably from 20 to 80% byweight, more preferably from 30 to 70% by weight of the total weight ofthe nonvolatile component therein.

[(B) Ethylenic Unsaturated Bond-Having Compound]

The ethylenic unsaturated bond-having compound (B) for use in theinvention is an addition-polymerizable compound having at least oneethylenic unsaturated double bond, and is selected from compounds havingat least one, preferably at least two ethylenic unsaturated bonds. Thecompound group is well known in the industrial field of the art, and anyone belonging to it may be used in the invention with no specificlimitation. For example, the compounds in the group have variouschemical morphologies of monomers, prepolymers, or that is, dimers,trimers and oligomers, as well as their mixtures and copolymers.Examples of the monomers and their copolymers are unsaturated carboxylicacids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonicacid, isocrotonic acid, maleic acid) and their esters, and amides.Preferred for use herein are esters of unsaturated carboxylic acids andaliphatic polyalcohols, and amides of unsaturated carboxylic acids andaliphatic polyamines. Also preferred for use herein areaddition-reaction products of unsaturated carboxylates or amides havinga nucleophilic substituent such as hydroxyl, amino or mercapto group andmonofunctional or polyfunctional isocyanates or epoxides; anddehydrating condensation products thereof with monofunctional orpolyfunctional carboxylic acids. In addition, also preferred areaddition-reaction products of unsaturated carboxylates or amides havingan electrophilic substituent such as isocyanate or epoxy group andmonofunctional or polyfunctional alcohols, amines or thiols; andsubstitution-reaction products of unsaturated carboxylates or amideshaving a removable substituent such as halogen or tosyloxy group andmonofunctional or polyfunctional alcohols, amines or thiols. As otherexamples, the above-mentioned unsaturated carboxylic acids may bereplaced with unsaturated phosphonic acids, styrenes or vinyl ethers,and the compounds of those groups are also usable herein.

Specific examples of monomers usable herein, esters of aliphaticpolyalcohols with unsaturated carboxylic acids are mentioned below.Acrylates include ethylene glycol diacrylate, triethylene glycoldiacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate,propylene glycol diacrylate, neopentylglycol diacrylate,trimethylolpropane triacrylate, trimethylolpropanetri(acryloyloxypropyl)ether, trimethylolethane triacrylate, hexanedioldiacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycoldiacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate,pentaerythritol tetraacrylate, dipentaerythritol diacrylate,dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitoltetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate,tri(acryloyloxyethyl)isocyanurate, and polyester acrylate oligomers.

Methacrylates include tetramethylene glycol dimethacrylate, triethyleneglycol dimethacrylate, neopentylglycol dimethacrylate,trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate,ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate,hexanediol dimethacrylate, pentaerythritol dimethacrylate,pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate,dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate,sorbitol trimethacrylate, sorbitol tetramethacrylate,bis[p-(3-methacryloxy-2-hydroxypropoxy)phenyl]-dimethylmethane, andbis[p-(methacryloxyethoxy)phenyl]dimethylmethane.

Itaconates include ethylene glycol diitaconate, propylene glycoldiitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate,tetramethylene glycol diitaconate, pentaerythritol diitaconate, andsorbitol tetraitaconate. Crotonates include ethylene glycol dicrotonate,tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, andsorbitol tetracrotonate. Isocrotonates include ethylene glycoldiisocrotonate, pentaerythritol diisocrotonate, and sorbitoltetraisocrotonate. Maleates include ethylene glycol dimaleate,triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitoltetramaleate.

Preferred examples of other esters are aliphatic alcohol esters as inJP-B 46-27926 and 51-47334, and JP-A 57-196231; those having an aromaticskeleton as in JP-A 59-5240, 59-5241 and 2-226149; and those having anamino group as in JP-A 1-165613. Mixtures of the above-mentioned estermonomers may also be used herein.

Specific examples of monomers, amides of aliphatic polyamines withunsaturated carboxylic acids, include methylene bisacrylamide,methylenebismethacrylamide, 1,6-hexamethylene bisacrylamide,1,6-hexamethylene bismethacrylamide, diethylenetriaminetrisacrylamide,xylylenebisacrylamide, and xylylene bismethacrylamide. Other preferredexamples of amide monomers are those having a cyclohexylene structure asin JP-B 54-21716.

In addition, urethane-based addition-polymerizable compounds producedthrough addition reaction of isocyanate and hydroxyl group are alsopreferred for use herein. For example, they include vinylurethanecompounds having at least two polymerizable vinyl groups in onemolecule, which are produced through addition reaction of apolyisocyanate compound having at least two isocyanate groups in onemolecule with a vinylmonomer having a hydroxyl group of the followingformula, such as those described in JP-B 48-41708.CH₂═C(R⁴)COOCH₂CH(R⁵)OHwherein, R⁴ and R⁵ each represent H or CH₃.

Also, urethane acrylates as in JP-A 51-37193, and JP-B 2-32293 and2-19765; and ethyleneoxide skeleton-having urethane compounds as in JP-B58-49860, 56-17654, 62-39417 and 62-39418 are also preferred for useherein. Further, addition-polymerizable compounds having an aminostructure or a sulfido structure in the molecule, as in JP-A 63-277653,63-260909 and 1-105238, provide rapidly-processable image-recordingmaterials.

Other examples also usable herein are polyfunctional acrylates andmethacrylates such as polyester acrylates, and epoxy acrylates preparedthrough reaction of epoxy resins and (meth)acrylic acids. In addition,further mentioned are specific unsaturated compounds described in JP-B46-43946, 1-40337, 1-40336; and vinylphosphonic acid compounds as inJP-A 2-25493. In some cases, perfluoroalkyl-containing structures as inJP-A 61-22048 are preferred. Further, photocurable monomers andoligomers as described in Nippon Secchaku Kyokai-Shi, Vol. 20, No. 7,pages 300 to 308 (1984) can be used.

In addition, compounds having at least two styrenic double bonds in themolecule are also preferably used herein. Concretely, they includecompounds having at least two functional groups of formula (D) or (E) inthe molecule. Specific examples of the compounds are mentioned below.

The details regarding the structure of the addition-polymerizablecompound, ethylenic-unsaturated bond-having compound (B), the mode ofusing it as to whether it is used alone or as combined with any other,and the amount thereof to be used may be determined in any desiredmanner depending on the performance design of the final polymerizablecomposition of the invention. For example, when the polymerizablecomposition of the invention is used in the recording layer of negativeimage-forming materials, then the compound (B) may be selected from thefollowing viewpoint. In point of the photosensitivity thereof, theunsaturated group content of the compound per molecule is preferablylarger. In many cases, bifunctional or more polyfunctional compounds arepreferred. For increasing the strength of the image area, or that is,the cured film containing it, trifunctional or more polyfunctionalcompounds are preferred. Further, compounds that differ in point of thenumber of the functional groups therein and of the type of thepolymerizable group therein (for example, acrylates, methacrylates,styrene compounds, vinyl ether compounds) may be combined to therebycontrol both the photosensitivity of the compound and the mechanicalstrength of the processed materials. Compounds having a large molecularweight and compounds having a high degree of hydrophobicity are good inpoint of the photosensitivity and the film strength, but are oftenunfavorable since their developability is not good and they may formdepositions in developer. In addition, the compatibility of thecomponent with other components (e.g., components (A), component (C),dye) in the image-recording layer of negative image-recording materialsand the dispersibility thereof in those components are also importantfactors in selecting and using the addition-polymerizable compound forthe component (B). For example, using low-purity compounds or combiningtwo or more different types of compounds may improve the compatibilityof the compounds with such other components.

In particular, when the polymerizable composition of the invention isused in the recording layer of lithographic printing plate precursors,then a specific structure may be selected for the compound (B) for thepurpose of increasing the adhesiveness of the recording layer to thesupport and the overcoat layer mentioned below of the plate precursors.The blend ratio of the addition-polymerizable compound in the recordinglayer will be preferably larger for higher sensitivity of the layer. Iftoo large, however, it may cause unfavorable phase separation or causesome problems in the process of producing the precursor owing to thestickiness of the recording layer (for example, the component of therecording layer may transfer or adhere to others to cause processfailure), or the excess compound will precipitate in developer. Fromthese viewpoints, the amount of the component (B),addition-polymerizable compound in the recording layer is preferablyfrom 5 to 80% by mass, more preferably from 25 to 75% by mass relativeto the nonvolatile component of the layer. Either singly or as combined,one or more compounds may be used for the component (B) in the layer.

When the polymerizable composition of the invention is applied tolithographic printing plate precursors in that manner, then thestructure, the blend ratio and the amount of the addition-polymerizablecompound for the component (B) may be suitably determined depending onvarious factors such as the degree of polymerization retardation byoxygen, the resolution, the fogging resistance, the refractivity changeand the surface stickiness. As the case may be, multi-layerconstitutions and coating methods of undercoating or overcoating mayapply to the plate precursors.

[(C) Compound of Generating Radical by Light or Heat]

The compound (C) of generating a radical by light or heat (hereinafterreferred to as radical generator) is for initiating and promoting thecuring reaction of the ethylenic unsaturated bond-having compound (B) inthe composition of the invention. The radical generator (C) is acompound which, when exposed to light or heat, decomposes under heat toform a radical. When the radical generator of the type is combined withthe sensitizing dye (D) mentioned below and when this is irradiated withlaser for exposure, then the sensitizing dye (D) may absorb the laserlight to generate heat, and the compound may generate a radical by thelight or heat. The combination enables high-sensitivity image formation.

Preferred examples of the radical generator for the component (C)include (a) an aromatic ketone, (b) an onium salt compound, (c) anorganic peroxide, (d) a thio compound, (e) a hexaarylbiimidazolecompound, (f) a ketoxime ester compound, (g) a borate compound, (h) anazinium compound, (i) a metallocene compound, (j) an active estercompound, and (k) a compound having a carbon-halogen bond. Specificexamples of (a) to (k) are mentioned below, to which, however, theinvention should not be limited.

(a) Aromatic Ketone:

Preferred examples of the aromatic ketone (a) include compounds having abenzophenone skeleton or a thioxantone skeleton as described in J. P.Fouassier and J. F. Rabek, Radiation Curing in Polymer Science andTechnology, pages 77 to 117 (1993).

More preferred examples of the aromatic ketone (a) includeα-thiobenzophenone compounds as in JP-B 47-6416; benzoin ether compoundsas in JP-B-47-3981; α-substituted benzoin compounds as in JP-B 47-22326;benzoin derivatives as in JP-B 47-23664; aroylphosphonates as in JP-A57-30704; dialkoxybenzophenones as in JP-B 60-26483; benzoin ethers asin JP-B 60-26403, JP-A 62-81345; α-aminobenzophenones as in U.S. Pat.No. 4,318,791, EP 0284561A1; p-di(dimethylaminobenzoyl)benzenes as inJP-A 2-211452; thio-substituted aromatic ketones as in JP-A 61-194062;acylphosphine sulfides as in JP-B 2-9597; acylphosphines as in JP-B2-9596; thioxanthones as in JP-B 63-61950; and coumarins as in JP-B59-42864.

(b) Onium Salt Compound:

The onium salt compound (b) includes iodonium salts, diazonium salts andsulfonium salts. In the invention, the onium salt compound functions notas an acid generator but as a radical generator. Preferred examples ofthe onium salt compound for use in the invention are those of thefollowing formulae (III) to (V).

In formula (III), Ar¹¹ and Ar¹² each independently represent anoptionally-substituted aryl group having up to 20 carbon atoms.Preferred examples of the substituent for the substituted aryl groupinclude a halogen atom, a nitro group, an alkyl group having up to 12carbon atoms, an alkoxy group having up to 12 carbon atoms, and anaryloxy group having up to 12 carbon atoms. Z¹¹⁻ represents a counterion selected from a halide ion, a perchlorate ion, a tetrafluoroborateion, a hexafluorophosphate ion, a carboxylate ion and a sulfonate ion,preferably a perchlorate ion, a hexafluorophosphate ion, a carboxylateion or an arylsulfonate ion.

In formula (IV), Ar²¹ represents an optionally-substituted aryl grouphaving up to 20 carbon atoms. Preferred examples of the substituent forthe substituted aryl group include a halogen atom, a nitro group, analkyl group having up to 12 carbon atoms, an alkoxy group having up to12 carbon atoms, an aryloxy group having up to 12 carbon atoms, analkylamino group having up to 12 carbon atoms, a dialkylamino grouphaving up to 12 carbon atoms, an arylamino group having up to 12 carbonatoms, and a diarylamino group having up to 12 carbon atoms. Z²¹⁻represents a counter ion, having the same meaning as that of Z¹¹⁻.

In formula (V), R³¹, R³² and R³³ may be the same or different, eachrepresenting an optionally-substituted hydrocarbon group having up to 20carbon atoms. Preferred examples of the substituent include a halogenatom, a nitro group, an alkyl group having up to 12 carbon atoms, analkoxy group having up to 12 carbon atoms, and an aryloxy group havingup to 12 carbon atoms. Z³¹⁻ represents a counter ion, having the samemeaning as that of Z¹¹⁻.

Specific examples of the onium salt compound preferred for the compound(C) of generating a radical by light or heat (radical generator) for usein the invention are, for example, as in JP-A2001-133696. Preferredexamples for use herein, onium salt compounds of formula (III) ([OI-1]to [OI-10], onium salt compounds of formula (IV) ([ON-1] to [ON-5], andonium salt compounds of formula (V) ([OS-1] to [OS-10] are mentionedbelow, to which, however, the invention should not be limited.

It is desirable that the onium salt compounds preferred for use in theinvention have a maximum absorption wavelength of 400 nm or less, morepreferably 360 nm or less. Using the compounds that have an absorptionwavelength in the UV range makes it possible to handle the polymerizablecomposition of the invention under white light.

(c) Organic Peroxide:

The organic peroxide (c) includes almost all organic compounds having atleast one oxygen-oxygen bond in the molecule thereof. Specific examplesof the organic peroxide include methyl ethyl ketone peroxide,cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide,methylcyclohexanone peroxide, acetylacetone peroxide,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane,tert-butylhydroperoxide, cumene hydroperoxide, diisopropylbenzenehydroperoxide, paramenthane hydroperoxide,2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, di-tert-butyl peroxide, tert-butylcumyl peroxide, dicumylperoxide, bis(tert-butylperoxyisopropyl)benzene,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-xanoyl peroxide,succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide,metatoluoyl peroxide, diisopropylperoxy dicarbonate,di-2-ethylhexylperoxy dicarbonate, di-2-ethoxyethylperoxy dicarbonate,dimethoxyisopropylperoxy dicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, tert-butylperoxy acetate, tert-butylperoxy pivalate,tert-butylperoxy neodecanoate, tert-butylperoxy octanoate,tert-butylperoxy-3,5,5-trimethyl hexanoate, tert-butylperoxy laurate,tertiary carbonate,3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-amylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-hexylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-octylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(cumylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(p-isopropylcumylperoxycarbonyl)benzophenone, carbonyldi(tert-butylperoxydihydrogen diphthalate), and carbonyldi(tert-hexylperoxydihydrogen diphthalate).

Of those, preferred are peroxides such as3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-amylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-hexylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-octylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(cumylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(p-isopropylcumylperoxycarbonyl)-benzophenone anddi-tert-butyldiperoxy isophthalate.

(d) Thio Compound:

The thio compound (d) includes compounds represented by the followingformula (15):

In formula (15), R²⁶ represents an alkyl group, an aryl group or asubstituted aryl group; R²⁷ represents a hydrogen atom or an alkylgroup; or R²⁶ and R²⁷ combine with each other and together represent anon-metallic atomic group necessary for forming a 5-membered, 6-memberedor 7-membered ring which may contain a hetero atom selected from anoxygen atom, a sulfur atom and a nitrogen atom.

The alkyl group in formula (15) is preferably that having from 1 to 4carbon atoms. The aryl group is preferably that having from 6 to 10carbon atoms, for example, phenyl and naphthyl groups. The substitutedaryl group includes the above-described aryl group substituted with, forexample, a halogen atom, e.g., chlorine, an alkyl group, e.g., methyl,or an alkoxy group, e.g., methoxy or ethoxy. R²⁷ preferably representsan alkyl group having from 1 to 4 carbon atoms. Specific examples of thethio compound represented by formula (15) include the followingcompounds: No. R²⁶ R²⁷ 1 —H —H 2 —H —CH₃ 3 —CH₃ —H 4 —CH₃ —CH₃ 5 —C₆H₅—C₂H₅ 6 —C₆H₅ —C₄H₉ 7 —C₆H₄Cl —CH₃ 8 —C₆H₄Cl —C₄H₉ 9 —C₆H₄—CH₃ —C₄H₉ 10—C₆H₄—OCH₃ —CH₃ 11 —C₆H₄—OCH₃ —C₂H₅ 12 —C₆H₄—OC₂H₅ —CH₃ 13 —C₆H₄—OC₂H₅—C₂H₅ 14 —C₆H₄—OCH₃ —C₄H₉ 15 —(CH₂)₂— 16 —(CH₂)₂—S— 17 —CH(CH₃)—CH₂—S—18 —CH₂—CH(CH₃)—S— 19 —C(CH₃)₂—CH₂—S— 20 —CH₂—C(CH₃)₂—S— 21 —(CH₂)₂—O—22 —CH(CH₃)—CH₂—O— 23 —C(CH₃)₂—CH₂—O— 24 —CH═CH—N(CH₃)— 25 —(CH₂)₃—S— 26—(CH₂)₂—CH(CH₃)—S— 27 —(CH₂)₃—O— 28 —(CH₂)₅— 29 —C₆H₄—O— 30—N═C(SCH₃)—S— 31 —C₆H₄—NH— 32

(e) Hexaarylbiimidazole Compound:

The hexaarylbiimidazole compound (e) includes lophine dimers asdescribed in JP-B45-37377 and 44-86516, specifically, for example,2,2′-bis(o-chlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-bromophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o,p-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-chlorophenyl)-4,4′,5,5′-tetra(m-methoxyphenyl)biimidazole,2,2′-bis(o,o′-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-nitrophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-methylphenyl)-4,4′, 55′-tetraphenylbiimidazole, and2,2′-bis(o-trifluoromethylphenyl)-4,4′,5,5′-tetraphenylbiimidazole.

(f) Ketoxime Ester Compound:

The ketoxime ester compound (f) includes, for example,3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one,3-propyonyloxyiminobutan-2-one, 2-acetoxyiminopentan-3-one,2-acetoxyimino-1-phenylpropan-1-one,2-benzoyloxyimino-1-phenylpropan-1-one,3-p-toluenesulfonyloxyiminobutan-2-one, and2-ethoxycarbonyloxyimino-1-phenylpropan-1-one.

(g) Borate Compound:

The borate compound (g) includes compounds represented by the followingformula (16):

In formula (16), R²⁸, R²⁹, R³⁰ and R³¹, which may be the same ordifferent, each represent a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, a substituted or unsubstitutedalkenyl group, a substituted or unsubstituted alkynyl group, or asubstituted or unsubstituted heterocyclic group, or at least two of R²⁸,R²⁹, R³⁰ and R³¹ may combine with each other to form a cyclic structure,provided that at least one of R²⁸, R²⁹, R³⁰ and R³¹ represents asubstituted or unsubstituted alkyl group; and (Z⁵)⁺ represents an alkalimetal cation or a quaternary ammonium cation.

The alkyl group represented by R²⁸ to R³¹ includes a straight chain,branched or cyclic alkyl group, and preferably has from 1 to 18 carbonatoms. Specific examples thereof include methyl, ethyl, propyl,isopropyl, butyl, pentyl, hexyl, octyl, stearyl, cyclobutyl, cyclopentyland cyclohexyl groups. The substituted alkyl group includes theabove-described alkyl group substituted with any of a halogen atom(e.g., chlorine or bromine), a cyano group, a nitro group, an aryl group(e.g., phenyl), a hydroxy group, —COOR³² (wherein R³² represents ahydrogen atom, an alkyl group having from 1 to 14 carbon atoms, or anaryl group) —OCOR³³ or —OR³⁴ (wherein R³³ and R³⁴ each represent analkyl group having from 1 to 14 carbon atoms, or an aryl group) or —OR³⁰(wherein R³⁰ represents an alkyl group having from 1 to 14 carbon atomsor an aryl group), and a group of the following formula:

wherein R³⁵ and R³⁶ each independently represent a hydrogen atom, analkyl group having from 1 to 14 carbon atoms, or an aryl group.

The aryl group represented by R²⁸ to R³¹ includes an aryl group havingfrom one to three rings, for example, phenyl or naphthyl. Thesubstituted aryl group includes the above-described aryl groupsubstituted with the substituent described for the substituted alkylgroup above or an alkyl group having from 1 to 14 carbon atoms. Thealkenyl group represented by R²⁸ to R³¹ includes a straight chain,branched or cyclic alkenyl group having from 2 to 18 carbon atoms. Inthe substituted alkenyl group, the substituent includes the substituentsdescribed for the substituted alkyl group above. The alkynyl grouprepresented by R²⁸ to R³¹ includes a straight chain, branched or cyclicalkynyl group having from 2 to 28 carbon atoms. In the substitutedalkynyl group, the substituent includes the substituents described forthe substituted alkyl group above. The heterocyclic group represented byR²⁸ to R³¹ includes a 5-membered or more heterocyclic group, preferablya 5-membered, 6-membered or 7-membered heterocyclic group, containing atleast one hetero atom selected from a nitrogen atom, a sulfur atom andan oxygen atom. The heterocyclic group may have a condensed ring. In thesubstituted heterocyclic group, the substituent includes thesubstituents described for the substituted aryl group above. Specificexamples of the compound represented by formula (16) include compoundsdescribed in U.S. Pat. Nos. 3,567,453 and 4,343,891, European Patents109,772 and 109,773.

(h) Azinium Compound:

The azinium compound (h) includes compounds having an N—O bond asdescribed in JP-A-63-138345, JP-A-63-142345, JP-A-63-142346,JP-A-63-143537 and JP-B-46-42363.

(i) Metallocene Compound:

The metallocene compound (i) includes titanocene compounds as describedin JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249 andJP-A-2-4705, and iron-arene complexes as described in JP-A-1-304453 andJP-A-1-152109.

(j) Active Ester Compounds:

The active ester compound (j) includes imidosulfonate compounds asdescribed in JP-B-62-6223, and active sulfonates as described inJP-B-63-14340 and JP-A-59-174831.

(k) Compound Having Carbon-Halogen Bond:

Preferred examples of the compound having a carbon-halogen bond (k)include compounds of the following formulae (17) to (23):

In formula (17), X² represents a halogen atom; Y¹ represents —C(X²)₃,—NH₂, —NHR³⁸, —N(R³⁸)₂ or —OR³⁸; R³ represents an alkyl group, asubstituted alkyl group, an aryl group, or a substituted aryl group; andR³⁷ represents —C(X²)₃, an alkyl group, a substituted alkyl group, anaryl group, a substituted aryl group, or a substituted alkenyl group.

In formula (18), R³⁹ represents an alkyl group, a substituted alkylgroup, an alkenyl group, a substituted alkenyl group, an aryl group, asubstituted aryl group, a halogen atom, an alkoxy group, a substitutedalkoxy group, a nitro group, or a cyano group; X³ represents a halogenatom; and n represents an integer of from 1 to 3.R⁴⁰-Z⁶-CH_((2-m))(X³)_(m)R⁴¹  (19)

In formula (19), R⁴⁰ represents an aryl group or a substituted arylgroup; R⁴¹ represents

or a halogen atom; Z⁶ represents —C(═O)—, —C(═S)— or —SO₂—.

R⁴² and R⁴³ each represent an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group, an aryl group, or asubstituted aryl group; R⁴⁴ has the same meaning as defined for R³⁸ informula (17); X³ represents a halogen atom; and m represents 1 or 2.

In formula (20), R⁴⁵ represents an optionally-substituted aryl orheterocyclic group; R⁴⁶ represents a trihaloalkyl or trihaloalkenylgroup having from 1 to 3 carbon atoms; and p represents 1, 2 or 3.

Formula (21) indicates carbonylmethylene heterocyclic compounds having atrihalogenomethyl group, in which L⁷ represents a hydrogen atom or agroup represented by formula —CO—(R⁷)_(q)(C(X⁴)₃)_(r); Q² represents asulfur atom, a selenium atom, an oxygen atom, a dialkylmethylene group,an alken-1,2-ylene group, a 1,2-phenylene group, or —N—R; M⁴ representsa substituted or unsubstituted alkylene or alkenylene group, or a1,2-arylene group; R⁴⁸ represents an alkyl group, an aralkyl group, oran alkoxyalkyl group; R⁴⁷ represents a divalent carbocyclic orheterocyclic aromatic group; X⁴ represents a chlorine atom, a bromineatom or an iodine atom; and q=1 and r=1, or q=1 and r=1 or 2.

Formula (22) indicates 4-halogeno-5-(halogenomethylphenyl)oxazolederivatives, in which X⁵ represents a halogen atom, t represents aninteger of from 1 to 3; s represents an integer of from 1 to 4; R⁴⁹represents a hydrogen atom or —CH_(3-t)X⁵ _(t); and R⁵⁰ represents anoptionally-substituted, s-valent unsaturated organic residue.

Formula (23) indicates 2-(halogenomethylphenyl)-4-halogeno-oxazolederivatives, in which X⁶ represents a halogen atom, v represents aninteger of from 1 to 3; u represents an integer of from 1 to 4; R⁵¹represents a hydrogen atom or —CH_(3-v)X⁶ _(v); and R⁵² represents anoptionally-substituted, u-valent unsaturated organic residue.

Specific examples of the compound having a carbon-halogen bond includecompounds as described in Wakabayashi et al., Bull. Chem. Soc. Japan,Vol. 42, page 2924 (1969). In addition, they include compounds asdescribed in British Patent 1,388,492, for example,2-styryl-4,6-bis(trichloromethyl)-S-triazine,2-(p-methylstyryl)-4,6-bis(trichloromethyl)-S-triazine,2-(p-methoxylstyryl)-4,6-bis(trichloromethyl)-S-triazine, and2-(p-methoxylstyryl)-4-amino-6-trichloromethyl-S-triazine; and compoundsas described in JP-A-53-133428 and German Patent 3,337,024.

In addition, further mentioned are compounds as described in F. C.Schaefer et al., J. Org. Chem., Vol. 29, page 1527 (1964); and compoundsas described in JP-A-62-58241.

Further mentioned are compounds as described in JP-A-5-281728.

Still further mentioned are compounds which can be easily synthesized byone skilled in the art according to synthesis methods as described in M.P. Hutt, E. F. Elslager and L. M. Herbel, Journal of HeterocyclicChemistry, Vol. 7, No. 3, page 511, f.f. (1970).

More preferred examples of the radical generator for use in theinvention include the aromatic ketone (a), the onium salt compound (b),the organic peroxide (c), the hexaarylbiimidazole compound (e), themetallocene compound (i) and the compound having a carbon-halogen bond(k) as described above. Still more preferred examples thereof includearomatic iodonium salts, aromatic diazonium salts, titanocene compoundsand trihalomethyl-S-triazine compounds of formula (17).

Oxime ester compounds preferred for the compound (C) of generating aradical by light or heat for use in the invention are described.Preferred examples of oxime ester compounds for use herein arerepresented by the following formula (i):

In formula (i), X represents a carbonyl group, a sulfone group, or asulfoxide group; Y represents a cyclic or straight chain alkyl, alkenylor alkynyl group having from 1 to 12 carbon atoms, an aryl group havingfrom 6 to 18 carbon atoms, or a heterocyclic group. The aryl groupincludes aromatic hydrocarbon compounds such as abenzene ring, anaphthalene ring, an anthracene ring, a phenanthrene ring, a pyrenegroup, and a triphenylene group. The heterocyclic group includesaromatic compounds having at least one hetero atom of nitrogen, sulfurand oxygen atoms in the cyclic structure thereof, for example, a pyrrolegroup, a furan group, a thiophene group, a selenophene group, a pyrazolegroup, an imidazole group, a triazole group, a tetrazole group, anoxazole group, a thiazole group, an indole group, a benzofuran group, abenzimidazole group, a benzoxazole group, a benzothiazole group, apyridine group, a pyrimidine group, a pyrazine group, a triazine group,a quinoline group, a carbazole group, an acridine group, a phenoxazinegroup, and a phenothiazine group. These substituents for Y may befurther substituted with any of a halogen atom, a hydroxyl group, anitrile group, a nitro group, a carboxyl group, an aldehyde group, analkyl group, a thiol group, an aryl group, an alkenyl group, an alkynylgroup, an ether group, an ester group, an urea group, an amino group, anamido group, a sulfido group, a disulfido group, a sulfoxide group, asulfo group, a sulfone group, a hydrazine group, a carbonyl group, animino group, a halogen atom, a hydroxyl group, a nitrile group, a nitrogroup, a carboxyl group, a carbonyl group, an urethane group, an alkylgroup, a thiol group, an aryl group, a phosphoroso group, a phosphogroup, or a carbonyl-ether group.

In formula (i), Z has the same meaning as Y, representing a nitrilegroup, a halogen atom, a hydrogen atom or an amino group. Thesesubstituents for Z may be further substituted with any of a halogenatom, a hydroxyl group, a nitrile group, a nitro group, a carboxylgroup, an aldehyde group, an alkyl group, a thiol group, an aryl group,an alkenyl group, an alkynyl group, an ether group, an ester group, anurea group, an amino group, an amido group, a sulfido group, a disulfidogroup, a sulfoxide group, a sulfo group, a sulfone group, a hydrazinegroup, a carbonyl group, an imino group, a halogen atom, a hydroxylgroup, a nitrile group, a nitro group, a carboxyl group, a carbonylgroup, an urethane group, an alkyl group, a thiol group, an aryl group,a phosphoroso group, a phospho group, or a carbonyl-ether group.

In formula (i), W represents a divalent organic group, for example, amethylene group, a carbonyl group, a sulfoxide group, a sulfone group,or an imino group The methylene group and the imino group may besubstituted with any of an alkyl group, an aryl group, an ester group, anitrile group, a carbonyl-ether group, a sulfo group, a sulfo-ethergroup, or an ether group. n indicates an integer of 0 or 1.

In formula (i), V represents a cyclic or straight chain alkyl, alkenylor alkynyl group having from 1 to 12 carbon atoms, an aryl group havingfrom 6 to 18 carbon atoms, an alkoxy group, or an aryloxy group. Thearyl group includes aromatic hydrocarbon compounds such as abenzenering, a naphthalene ring, an anthracene ring, a phenanthrene ring, apyrene group, and a triphenylene group; and hetero atom-containingaromatic compounds such as a pyrrole group, a furan group, a thiophenegroup, a selenophene group, a pyrazole group, an imidazole group, atriazole group, a tetrazole group, an oxazole group, a thiazole group,an indole group, a benzofuran group, a benzimidazole group, abenzoxazole group, a benzothiazole group, a pyridine group, a pyrimidinegroup, a pyrazine group, a triazine group, a quinoline group, acarbazole group, an acridine group, a phenoxazine group, and aphenothiazine group. These substituents for V may be further substitutedwith any of a halogen atom, a hydroxyl group, a nitrile group, a nitrogroup, a carboxyl group, an aldehyde group, an alkyl group, a thiolgroup, an aryl group, an alkenyl group, an alkynyl group, an ethergroup, an ester group, an urea group, an amino group, an amido group, asulfido group, a disulfido group, a sulfoxide group, a sulfo group, asulfone group, a hydrazine group, a carbonyl group, an imino group, ahalogen atom, a hydroxyl group, a nitrile group, a nitro group, acarboxyl group, a carbonyl group, an urethane group, an alkyl group, athiol group, an aryl group, a phosphoroso group, a phospho group, or acarbonyl-ether group.

V and Z may bond to each other to form a ring.

In the oxime ester compounds of formula (i), it is desirable that X is acarbonyl group, Y is an aryl or benzoyl group, Z is an alkyl or arylgroup, W is a carbonyl group, and V is an aryl group in view of thesensitivity of the compounds. More preferably, the aryl group for V hasa thioether substituent.

Regarding the structure thereof, the N—O bond in formulas (i) may formeither an E-form or a Z-form.

Other oxime ester compounds favorable for the invention are described inProgress in Organic Coatings, 13 (1985), 123-150; J. C. S. Perkin II(1979), 1653-1660; Journal of Photopolymer Science and Technology(1995), 205-232; J. C. S. Perkin II (1979), 156-162; JP-A2000-66385; andJP-A2000-80068.

Specific examples of oxime ether compounds favorable for the inventionare mentioned below, to which, however, the invention should not belimited.

The amount of the compound (C) of generating a radical by light or heatto be in the polymerizable composition of the invention may be, forexample, when the composition is used in the recording layer of negativeimage-recording materials, from 0.1 to 50 by mass, preferably from 0.5to 30% by mass, more preferably from 1 to 20% by mass relative to thetotal solid content of the image-recording layer from the viewpoint ofthe sensitivity of the composition and of the staining resistancethereof in the non-image area in prints. Either singly or as combined,one or more different types of the compounds (C) may be used. Thecompound (C) may be combined with the other components of thecomposition to be in one layer, or may be added to an additional layerthat differ from the layer that contain the other components.

[(D) Sensitizing Dye]

A sensitizing dye that absorbs light having a predetermined wavelengthis preferably added to the polymerizable composition of the invention.When the composition is exposed to light which the sensitizing dyetherein may absorb, then the radical generator (C) generates a radicaland the polymerization of the component (B) is thereby promoted. For thesensitizing dye (D), usable are known spectral-sensitizing dyes ordyestuffs, as well as dyes or pigments that absorb light to interactwith the radical initiator. Depending on the wavelength of the lightthat the sensitizing dye absorbs, the polymerizable composition of theinvention is sensitive to any of UV light, visible light or IR lighthaving different wavelengths. For example, when an IR absorbent is usedfor the sensitizing dye (D), then the polymerizable composition issensitive to IR light having a wavelength of from 760 nm to 1200 nm.

(Spectral-Sensitizing Dye or Dyestuff)

Preferred examples of the spectral-sensitizing dye or dyestuff for thesensitizing dye (D) for use in the invention include multi-nucleararomatic compounds (for example, pyrene, perylene, triphenylene),xanthenes (for example, Fluoresceine, Eosine, Erythrosine, Rhodamine B,Rose Bengale), cyanines (for example, thiacarbocyanine,oxacarbocyanine), merocyanines (for example, merocyanine,carbomerocyanine), thiazines (for example, Thionine, Methylene Blue,Toluidine Blue), acridines (for example, Acridine Orange, chloroflavine,acriflavine), phthalocyanines (for example, phthalocyanine,metallo-phthalocyanine), porphyrins (for example, tetraphenyl porphyrin,center metal-substituted porphyrin), chlorophylls (for example,chlorophyll, chlorophyllin, center metal-substituted chlorophyll), metalcomplexes (for example, the following compound), anthraquinones (forexample, anthraquinone), and aquariums (for example, aquarium).

More preferred examples of the spectral sensitizing dye or dyestuff foruse herein are mentioned below.

Styryl dyes as in JP-B 37-13034; cation dyes as in JP-A 62-143044;quinoxalinium salts as in JP-B59-24147; new methylene blue compounds asin JP-A 64-33104; anthraquinones as in JP-A 64-56767; benzoxanthene dyesas in JP-A 2-1714; acridines as in JP-A 2-226148, 2-226149; pyryliumsalts as in JP-B 40-28499; cyanines as in JP-B 46-42363; benzofuran dyesas in JP-A2-63053; conjugated ketone dyes as in JP-A 2-85858, 2-216154;dyes as in JP-A 57-10605; azocinnamylidene derivatives as in JP-B2-30321; cyanine dyes as in JP-A 1-287105; xanthene dyes as in JP-A62-31844, 62-31848, 62-143043; aminostyryl ketones as in JP-B 59-28325;dyes as in JP-A 2-179643; merocyanine dyes as in JP-A 2-244050;merocyanine dyes as in JP-B 59-28326; merocyanine dyes as in JP-A59-89303; merocyanine dyes as in Japanese Patent Application No.6-269047; and benzopyran dyes as in Japanese Patent Application No.7-164583.

(IR Absorbent)

In addition, the following IR (infrared) absorbents (dyes or pigments)are also favorably used for the sensitizing dye (D).

Commercially-available dyes such as those known, for example, inDyestuff Handbook (edited by the Organic Synthetic Chemical Society ofJapan, 1960) may be used herein. Concretely mentioned are azo dyes,metal complex salt azo dyes, pyrazolonazo dyes, naphthoquinone dyes,anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoniminedyes, methine dyes, cyanine dyes, squalilium dyes, pyrylium dyes, andmetal thiolate complex dyes.

Preferred for use herein are, for example, cyanine dyes as in JP-A58-125246, 59-84356, 59-202829, 60-78787; methine dyes as in JP-A58-173696, 58-181690, 58-194595; naphthoquinone dyes as in JP-A58-112793, 58-224793, 59-48187, 59-73996, 60-52940, 60-63744; squaliliumdyes as in JP-A 58-112792; and cyanine dyes as in British Patent434,875.

In addition, also preferred for use herein are near-IR absorbingsensitizers as in U.S. Pat. No. 5,156,938; arylbenzo(thio)pyrylium saltsas in U.S. Pat. No. 3,881,924; trimethinethiapyrylium salts as in JP-A57-142645 (U.S. Pat. No. 4,327,169); pyrylium compounds as in JP-A58-181051, 58-220143, 59-41363, 59-84248, 59-84249, 59-146063,59-146061; cyanine dyes as in JP-A 59-216146; pentamethinethiopyryliumsalts as in U.S. Pat. No. 4,283,475; and pyrylium compounds as in JP-B5-13514, 5-19702. Other preferred examples of dyes for use herein arenear-IR absorbent dyes of formulae (I) and (II) described in U.S. Pat.No. 4,756,993.

Still other preferred examples of IR-absorbent dyes for use in theinvention are specific indolenine-cyanine dyes as in Japanese PatentApplication Nos. 2001-6326 and 2001-237840, for example, those mentionedbelow.

Of those dyes, especially preferred for use in the invention are cyaninedyes, squalilium dyes, pyrylium salts, nickel-thiolate complexes, andindolenine-cyanine dyes. More preferred are cyanine dyes andindolenine-cyanine dyes; and even more preferred are cyanine dyes of thefollowing formula (a)

In formula (a), X¹ represents a hydrogen atom, a halogen atom, —NPh₂,X²-L¹ or a group mentioned below. X² represents an oxygen atom, anitrogen atom, or a sulfur atom; L¹ represents a hydrocarbon grouphaving from 1 to 12 carbon atoms, a hetero atom-containing aromaticgroup, a hetero atom-containing hydrocarbon group having from 1 to 12carbon atoms. The hetero atom as referred to herein includes N, S, O,halogen atoms, and Se. Xa⁻ has the same meaning as Za⁻ mentioned below.R^(a) represents a hydrogen atom, or a substituent selected from analkyl group, an aryl group, a substituted or unsubstituted amino group,or a halogen atom.

R¹ and R² each independently represent a hydrocarbon group having from 1to 12 carbon atoms. In view of the storage stability of the coatingliquid for recording layer, it is desirable that R¹ and R² areindependently a hydrocarbon group having 2 or more carbon atoms, morepreferably R¹ and R² bond to each other to form a 5-membered or6-membered ring.

Ar¹ and Ar² may be the same or different, each representing anoptionally-substituted aromatic hydrocarbon group. Preferred examples ofthe aromatic hydrocarbon group are a benzene ring and a naphthalenering. Preferred examples of the substituent for the group include ahydrocarbon group having up to 12 carbon atoms, a halogen atom, and analkoxy group having up to 12 carbon atoms. Y¹ and Y² may be the same ordifferent, each representing a sulfur atom, or a dialkylmethylene grouphaving up to 12 carbon atoms. R³ and R⁴ may be the same or different,each representing an optionally-substituted hydrocarbon group having upto 20 carbon atoms. Preferred examples of the substituent for the groupinclude an alkoxy group having up to 12 carbon atoms, a carboxyl group,and a sulfo group. R⁵, R⁶, R⁷ and R⁸ may be the same or different, eachrepresenting a hydrogen atom, or a hydrocarbon group having up to 12carbon atoms. In view of the easy availability of the starting materialsfor the compounds, they are preferably hydrogen atoms. Za⁻ represents acounter anion. However, when the cyanine dye of formula (a) has ananionic substituent in its structure and therefore does not requirecharge neutralization, then Za⁻ may be omitted. In view of the storagestability of the coating liquid for recording layer, Za⁻ is preferably ahalide ion, a perchlorate ion, a tetrafluoroborate ion,hexafluorophosphate ion, or sulfonate ion, more preferably a perchlorateion, a hexafluorophosphate ion, or an arylsulfonate ion.

Preferred examples of the cyanine dyes of formula (a) favorable for usein the invention are described in paragraphs [0017] to [0019] inJP-A2001-133969; paragraphs [0012] to [0038] in JP-A 2002-40638; andparagraphs [0012] to [0023] in JP-A 2002-23360.

Pigments usable in the invention are, for example,commercially-available pigments and pigments described in Color Index(C.I.); Newest Pigment Handbook (edited by the Pigment TechnologyAssociation of Japan, 1977); Newest Pigment Application Technology (CMCPublishing, 1986); Printing Ink Technology (CMC Publishing, 1984).

Various types of pigments are usable herein, including, for example,black pigments, yellow pigments, orange pigments, brown pigments, redpigments, purple pigments, blue pigments, green pigments, fluorescentpigments, metal powder pigments, and polymer-bonding dyes. Specificexamples of the pigments include insoluble azo pigments, azo lakepigments, condensed azo pigments, chelate azo pigments, phthalocyaninepigments, anthraquinone pigments, perylene pigments, perinone pigments,thioindigo pigments, quinacridone pigments, dioxazine pigments,isoindolinone pigments, quinophthalone pigments, Reichardt's dyes, azinepigments, nitroso pigments, nitro pigments, natural pigments,fluorescent pigments, inorganic pigments, and carbon black. Of thepigments, carbon black is preferably used.

The pigment may be used without surface treatment or the pigmentsubjected to the surface treatment may be used. Methods of the surfacetreatment include applying a resin or wax on the surface of pigment,applying a surface active agent to the surface of pigment, and bonding areactive substance (e.g., silane coupling agent, epoxy compound,polyisocyanate) to the surface of pigment. The methods of surfacetreatment are described in Properties and Applications of Metal Soap(Miyuki Shobo); Printing Ink Technology (CMC Publishing, 1984), andNewest Pigment Application Technology (CMC Publishing, 1986).

Preferably, the particle size of the pigment is from 0.01 μm to 10 μm,more preferably from 0.05 μm to 1 μm, even more preferably from 0.1 μmto 1 μm, from the viewpoint of the dispersibility of the pigment intocoating liquid and of the uniformity of the recording layer formed.

Known dispersing techniques used in production of ink and toner can beutilized for dispersing the pigment. A dispersing machine, for example,an ultrasonic dispersing device, a sand mill, an attritor, a pearl mill,a super mill, a ball mill, an impeller, a disperser, a KD mill, acolloid mill, Dynatron, a three-roll mill or a pressure kneader can beused for pigment dispersion. Details thereof are described in NewestPigment Application Technology (CMC Publishing, 1986).

When the polymerizable composition of the invention is used in therecording layer of negative image-recording materials, then thesensitizing dye (D) for promoting the curing reaction of thepolymerizable composition may be directly added to the recording layeralong with the other components thereto, but may be added to anadditional layer formed adjacent to the recording layer to attain thesame effect as in the former.

In particular, when the polymerizable composition of the invention isused in the recording layer of lithographic printing plate precursors,then the recording layer preferably has an optical density of from 0.1to 3.0 at an absorption maximum falling within a wavelength range offrom 300 nm to 1200 nm in view of the sensitivity thereof. Since theoptical density is determined depending on the amount of the sensitizingdye added to the recording layer and the thickness of the layer, thepredetermined optical density of the recording layer can be attained bycontrolling the two conditions.

The optical density of the recording layer can be measured in any knownmanner. For example, employable is a method comprising forming, on atransparent or white support, a recording layer having a thicknesssuitably determined within a range of dried coating amount necessary forlithographic printing plates followed by measuring the optical densitythereof with a transmission optical densitometer; or a method comprisingforming a recording layer on a reflective support of aluminium or thelike followed by measuring the reflection density of the layer.

[Other Components]

In addition to the above-mentioned indispensable components, thepolymerizable composition of the invention may contain any otheroptional component such as polymerization inhibitor, colorant andplasticizer, depending on the use and the production method thereof.Preferred additives to the polymerizable composition especially for usein the recording layer of negative image-recording materials arementioned below.

(Polymerization Inhibitor)

It is desirable that a small amount of a thermal polymerizationinhibitor is added to the polymerizable composition in order to preventundesirable thermal polymerization of the compound having apolymerizable ethylenic unsaturated double bond during the productionand preservation of the composition. Suitable examples of the thermalpolymerization inhibitor include hydroquinone, p-methoxyphenol,di-tert-butyl-p-cresol, pyrogallol, tert-butylcatechol, benzoquinone,4,4′-thiobis(3-methyl-6-tert-butylphenol),2,2′-methylenebis(4-methyl-6-tert-butylphenol) andN-nitrosophenylhydroxylamine cerous salt. The amount of the thermalpolymerization inhibitor to be added is preferably from about 0.01 toabout 5% by mass based on the total components of the composition. Also,if desired, a higher fatty acid derivative, for example, behenic acid orbehenic acid amide may be added so as to be maldistributed on thesurface of the recording layer during the drying process after thecoating of the polymerizable composition in order to prevent thepolymerization inhibition due to oxygen. The amount of the higher fattyacid derivative to be added is preferably from about 0.5 to about 10% bymass based on the total components of the composition.

(Colorant)

When the polymerizable composition of the invention is used in therecording layer of lithographic printing plate precursors, the dye orpigment may be added to the composition for the purpose of coloring therecording layer. By the addition of such colorant, a printing plate canbe improved in plate inspection properties, for example, visibilityafter the plate-making or suitability for image density measurement. Thecolorant to be used is preferably pigment because many dyes causereduction in the sensitivity of the photopolymerizable recording layer.Specific examples of the colorant include pigments, for example,phthalocyanine pigments, azo pigments, carbon black or titanium oxide,and dyes, for example, Ethyl Violet, Crystal Violet, azo dyes,anthraquinone dyes and cyanine dyes. The amount of the dye or pigment tobe added is preferably from about 0.5 to about 5% by mass based on thetotal components of the composition.

(Other Additives)

Known other additives may be added to the polymerizable composition ofthe invention. They include, for example, inorganic filler orplasticizer for improving the physical properties of hardened films, andoleosensitizer for improving the ink acceptability of the surface ofrecording layers, when the polymerizable composition of the invention isused in the recording layer of lithographic printing plates.

Examples of the plasticizer include dioctyl phthalate, didodecylphthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate,tricresyl phosphate, dioctyl adipate, dibutyl sebacate, and triacetylglycerin. The amount of the plasticizer to be added may be generally atmost 10% by mass based on the total amount of the polymer binder and theaddition-polymerizable compound in the composition. Furthermore, inorder to improve the film strength (printing durability), UV initiatorand thermal crosslinking agent capable of accelerating the effect ofheating and/or exposure to light after development may also be added.

Negative image-recording materials where the recording layer containsthe polymerizable composition of the invention may be fabricated bydissolving the constitutive components of the recording layer in asuitable organic solvent followed by applying the resulting solutiononto a support.

The solvent includes acetone, methyl ethyl ketone, cyclohexane, ethylacetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycolmonomethyl ether, ethylene glycolmonoethyl ether, ethylene glycoldimethyl ether, propylene glycol monomethyl ether, propylene glycolmonoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol,ethylene glycol monomethyl ether acetate, ethylene glycol monoethylether acetate, ethylene glycol monoisopropyl ether, ethylene glycolmonobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol,diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,propylene glycol monomethyl ether acetate, propylene glycol monoethylether acetate, 3-methoxypropyl acetate, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, methyl lactate, and ethyl lactate. Thesolvents may be used individually or in combination of two or morethereof. The solid concentration in the coating solution is suitablyfrom 2 to 50% by mass.

Since the coating amount of the image-recording layer on a support hasan influence mainly upon the sensitivity of the layer, thedevelopability, the strength of the exposed film and the printingdurability, it is desirable to appropriately determine the coatingamount thereof depending on the use. When the coating amount is toosmall, the printing durability may not be sufficient, whereas anexcessively large coating amount is disadvantageous, because thesensitivity decreases, the exposure takes a lot of time and thedevelopment also requires a longer period of time.

Especially in lithographic printing plate precursors for scanningexposure, to which negative image-recording materials are favorable, thedry coating amount of the recoding layer is preferably from about 0.1 toabout 10 g/m², more preferably from 0.5 to 5 g/m².

[Support]

Various types of support may be used in negative image-recordingmaterials where the polymerizable composition of the invention is used,with no limitation. Preferably used are hydrophilic supports known inthe art and generally used in lithographic printing plate precursors.

The support for use herein is preferably a dimensionally stableplate-like material. Examples thereof include paper, paper laminatedwith plastics (e.g., polyethylene, polypropylene or polystyrene), aplate of metal (e.g., aluminum, zinc or copper), a film of plastics(e.g., cellulose diacetate, cellulose triacetate, cellulose propionate,cellulose butyrate, cellulose acetate butyrate, cellulose nitrate,polyethylene terephthalate, polyethylene, polystyrene, polypropylene,polycarbonate or polyvinyl acetal) and paper or a plastic film laminatedwith or having deposited thereon the above-described metal. The surfaceof the support may be subjected to a known appropriate physical orchemical treatment, if desired, for the purpose of, for example,imparting hydrophilicity thereto or increasing the strength thereof.

Paper, a polyester film and an aluminum plate are preferably used. Ofthe supports, the aluminum plate is particularly preferred because it isdimensionally stable, relatively inexpensive and capable of providing asurface excellent in the hydrophilicity and strength by a surfacetreatment, if desired. Also, a composite sheet obtained by bonding analuminum sheet onto a polyethylene terephthalate film as described inJP-B-48-18327 is preferably used.

The aluminum plate suitably used includes a pure aluminum plate or analloy plate mainly comprising aluminum and containing a trace amount offoreign elements. Also, a plastic film laminated with or havingdeposited thereon aluminum may be used. In the following description,“aluminium support” is a generic term for the above-mentioned aluminiumor aluminium alloy supports. Examples of the foreign element containedin the aluminum alloy include silicon, iron, manganese, copper,magnesium, chromium, zinc, bismuth, nickel and titanium. The foreignelement content of the alloy is at most 10% by mass. In the invention,although pure aluminum is particularly suitably used, it is difficult toproduce completely pure aluminum in view of the refining technology.Thus, aluminum containing a trace amount of foreign elements can beused. The composition of the aluminum plate for use in the invention isnot particularly limited and an aluminum plate conventionally known andused in the art can be appropriately used herein. For example, hereinusable are JIS A 1050, JIS A 1100, JIS A 3103, and JIS A 3005.

The aluminum support for use in the invention preferably has a thicknessof approximately from 0.1 to 0.6 mm. The thickness may be suitablycontrolled depending on the use of the negative image-recordingmaterials to which the invention is applied. For example, when thenegative image-recording material is used for lithographic printingplate precursors, then the support size may be suitably determined inaccordance with the size of the printer to be used, the size of theprinting plate to be produced and the users' request. If desired, thealuminium support may be subjected to surface treatment as in the mannermentioned below. Needless-to-say, it may not be subjected to thetreatment.

(Surface-Roughening Treatment)

The surface-roughening treatment employable herein include mechanicalsurface-roughening, chemical etching and electrolytic graining as inJP-A56-28893. Also employable are electrochemical surface-roughening tobe effected in an electrolytic solution of hydrochloric acid or nitricacid; and mechanical surface-roughening such as wire brush graining tobe effected by the use of a metal wire applied onto the surface ofaluminium, ball graining to be effected by the use of abrasive balls andabrasive agent, or brush graining to be effected by the use of nylonbrush and abrasive agent. The surface-roughening methods may be effectedindividually or as combined. Above all, electrochemical surface-roughingto be effected in an electrolytic solution of hydrochloric acid ornitric acid is preferably used, in which the quantity of electricity tothe anode is from 50 C/cm² to 400 C/cm². More concretely, it isdesirable that to electrolyze aluminium in a mode of alternating currentand/or direct current electrolysis, in an electrolytic solutioncontaining from 0.1 to 50% hydrochloric acid or nitric acid, at atemperature falling between 20 and 80° C., for a period of time fallingbetween 1 second and 30 minutes, at a current density falling between100 C/cm² and 400 C/cm².

The aluminium support thus surface-roughened in the manner as above maybe chemically etched with acid or alkali. The etchant preferably usedfor it includes sodium hydroxide, sodium carbonate, sodium aluminate,sodium metasilicate, sodium phosphate, potassium hydroxide, lithiumhydroxide. The preferred range of the concentration and the temperaturefalls between 1 and 50%, and between 20 and 100° C., respectively. Theetched support is then desmutted with acid for removing the smutremaining on the etched surface. The acid to be used includes nitricacid, sulfuric acid, phosphoric acid, chromium acid, hydrofluoric acid,borohydrofluoric acid. Preferred embodiments of the desmutting treatmentafter the electrochemical surface-roughening treatment are a method ofcontacting the etched support with 15 to 65 mass % sulfuric acid at 50to 90° C. as in JP-A 53-12739; and an alkali-etching method as in JP-B48-28123. Thus treated in the manner as above, the center line meanroughness Ra of the treated surface is preferably from 0.2 to 0.5 μm,for which the method and the condition of surface-roughening treatmentare not specifically defined.

(Anodic Oxidation)

Preferably, the aluminium support treated in the manner as above is thensubjected to anodic oxidation.

Sulfuric acid, phosphoric acid, oxalic acid, or aqueous solution ofboric acid/sodium borate may be used either singly or as combined forthe essential ingredient of the electrolytic bath for the anodicoxidation. The electrolytic solution may contain the components that aregenerally in at least Al alloy plates, electrodes, tap water andunderground water. In addition, any additional second and thirdcomponents may also be added to it. The second and third components asreferred to herein include, for example, cations such as metal ions ofNa, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and ammoniumion; and anions such as nitrate ion, carbonate ion, chloride ion,phosphate ion, fluoride ion, nitrite ion, titanate ion, silicate ion,borate ion. The concentration of the additional components may be from 0to 1000 ppm or so. The condition for the anodic oxidation is notspecifically defined. Preferably, the aluminium support may be processedin a mode of direct current or alternating current electrolysis, in anamount of from 30 to 500 g/liter at a processing liquid temperaturefalling between 10 and 70° C., and at a current density falling between0.1 and 40 A/m². The thickness of the oxide film to be formed may befrom 0.5 to 1.5 μm, preferably from 0.5 to 1.0 μm. Preferably, theprocessing condition is so defined that the diameter of the microporesto be in the oxide film formed through the anodic oxidation on thesupport could be from 5 to 10 nm, and the pore density could be from8×10¹⁵ to 2×10¹⁶/m².

For hydrophilicating the surface of the support, any known method isemployable. One preferred treatment is hydrophilication with silicate orpolyvinylphosphonic acid. Through the treatment, a hydrophilic film maybe formed, having an Si or P content of from 2 to 40 mg/m², preferablyfrom 4 to 30 mg/m². The coating amount may be determined throughfluorescent X-ray spectrometry.

For example, the hydrophilication may be effected as follows: Analuminium support having an oxide film formed thereon through anodicoxidation is dipped in an aqueous solution that contains from 1 to 30%by mass, preferably from 2 to 15% by mass of an alkali metal silicate orpolyvinylphosphonic acid and has a pH at 25° C. of from 10 to 13, forexample, at 15 to 80° C. for 0.5 to 120 seconds.

The alkali metal silicate to be used for the hydrophilication includessodium silicate, potassium silicate, lithium silicate. A hydroxide maybe used for increasing the pH of the aqueous solution of alkali metalsilicate, and it includes sodium hydroxide, potassium hydroxide, lithiumhydroxide. If desired, an alkaline earth metal salt or a Group-IVB metalsalt may be added to the processing solution. The alkaline earth metalsalt includes nitrates such as calcium nitrate, strontium nitrate,magnesium nitrate, barium nitrate; and other water-soluble salts such assulfates, chlorides, phosphates, oxalates, borates. The Group-IVB metalsalt includes titanium tetrachloride, titanium trichloride, potassiumtitanium fluoride, potassium titanium oxalate, titanium sulfate,titanium tetraiodide, zirconium oxychloride, zirconium dioxide,zirconium oxychloride, zirconium tetrachloride.

The alkaline earth metal salt and the Group-IVB metal salt may be usedeither singly or as combined. The preferred range of the amount of thesalt to be used may be from 0.01 to 10% by mass, more preferably from0.05 to 5.0% by mass. In addition, silicate electrode position as inU.S. Pat. No. 3,658,662 is also effective. The electro-grained supportas in JP-B 46-27481 or JP-A 52-58602 or 52-30503 may be surface-treatedin a combined mode of anodic oxidation and hydrophilication as above,for use in the invention.

(Interlayer)

In the negative image-recording materials in which the polymerizablecomposition of the invention is used in the recording layer, aninterlayer (this may be referred to as “undercoat layer”) may beprovided between the image-recording layer and the support for improvingthe adhesiveness therebetween and improving the staining resistance ofthe processed materials. In particular, when the polymerizablecomposition of the invention is used in lithographic printing plateprecursors, the same interlayer may be provided therein. Specificexamples of the interlayer are described in JP-B 50-7481; JP-A 54-72104,59-101651, 60-149491, 60-2232998, 3-56177, 4-282637, 5-16558, 5-246171,7-159983, 7-314937, 8-202025, 8-320551, 9-34104, 9-236911, 9-269593,10-69092, 10-115931, 10-161317, 10-260536, 10-282682, 11-84647; JapanesePatent Application Nos. 8-225335, 8-270098, 9-195863, 9-195864, 9-89646,9-106068, 9-183834, 9-264311, 9-127232, 9-245419, 10-127602, 10-170202,11-36377, 11-165861, 11-284091, 2000-14697.

(Protective Layer)

When an image-recording material that contains the polymerizablecomposition in the recording layer thereof is processed to form an imagethereon, its exposure to light is generally effected in air. Therefore,it is desirable to provide a protective layer (this may be referred toas “overcoat layer”) on the image-recording layer. In particular, whenthe polymerizable composition is used in lithographic printing plateprecursors, the embodiment of forming such a protective layer therein ispreferred. The protective layer prevents oxygen and a low molecularsubstance, e.g., a basic substance present in the air, which inhibit theimage formation reaction caused in the recording layer upon exposure,from penetrating into the recording layer and thereby enables theexposure in the air. Accordingly, the protective layer is required tohave low permeability to a low molecular substance such as oxygen andpreferably further has capabilities of not substantially inhibit thetransmission of light used for the exposure, exhibiting excellentadhesion to the recording layer and being easily removed in developmentafter exposure. Investigations on the protective layer have been made asdescribed in detail in U.S. Pat. No. 3,458,311 and JP-A-55-49729.

Examples of the material which can be used in the protective layerinclude a water-soluble polymer compound having relatively goodcrystallinity. Specific examples thereof include a water-solublepolymer, for example, polyvinyl alcohol, polyvinyl pyrrolidone, acidiccellulose, gelatin, gum arabic or polyacrylic acid. Particularly,polyvinyl alcohol is preferably used as the main component of theprotective layer, because most advantageous results in the fundamentalproperties such as oxygen inhibiting property and developmentremovability can be obtained. The polyvinyl alcohol for use in theprotective layer has necessary oxygen inhibiting property and watersolubility, therefore, as long as it contains an unsubstituted vinylalcohol unit, a part thereof may be substituted with an ester, an etheror an acetal. Similarly, a part of the polymer may have anothercopolymer component. Examples of the polyvinyl alcohol which can be usedinclude those having a hydrolysis ratio of from 71 to 100 mol % and amolecular weight of from 300 to 2,400. Specific examples thereof includePVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS,PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220,PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420,PVA-613 and L-8 produced by Kuraray Co., Ltd.

The components of the protective layer (e.g., selection of PVA or use ofadditives) and the coating amount thereof are determined by takingaccount of fogging property, adhesive property and scratch resistance,in addition to the oxygen inhibiting property and the developmentremovability. In general, when PVA having a higher hydrolysis ratio(namely, the protective layer has a higher unsubstituted vinyl alcoholunit content) is used and the layer thickness is larger, the oxygeninhibiting property becomes stronger and this is more advantageous inview of sensitivity. However, if the oxygen inhibiting property isextremely increased, undesirable polymerization reaction may be causedduring the production or preservation, or undesirable fog or thickeningof image line may be generated during image exposure. Further, theadhesive property to the image area and the scratch resistance are alsovery important in view of handling the plate. Specifically, when ahydrophilic layer comprising a water-soluble polymer is coated on alipophilic recording layer, the layer is readily peeled off due toinsufficient adhesion. As a result, the peeled part may undergopolymerization inhibition by oxygen, therefore causing some defects offilm curing insufficiency. To overcome the problem, various proposalshave been made to improve the adhesive property between those twolayers. For example, in U.S. Patent Application Nos. 292,501 and 44,563,there are described techniques of mixing from 20 to 60% by mass of anacrylic emulsion or a water-insoluble vinyl pyrrolidone-vinyl acetatecopolymer in a hydrophilic polymer mainly comprising polyvinyl alcoholand applying the mixture to a recording layer, thereby obtaining asufficiently high adhesive property.

These known techniques can be applied to the protective layer for use inthe invention. A coating method of the protective layer is described indetail, for example, in U.S. Pat. No. 3,458,311 and JP-B 55-49729.

The negative image-recording material in which the polymerizablecomposition of the invention is used in the recording layer is processedfor at least exposure and development to record an image thereon. Inparticular, when the polymerizable composition of the invention is usedin lithographic printing plate precursors, they are processed throughexposure and development in the manner mentioned below, or processed indifferent methods, and they are thereby formed into printing plates.

A plate-making method from lithographic printing plate precursors wherethe polymerizable composition of the invention is used in the recordinglayer is described in detail hereinunder.

The source of light to which the lithographic printing plate precursoris exposed may be any known one with no limitation. Preferably, thewavelength of the light source falls between 300 nm and 100 nm.Concretely, various lasers are preferred for the light source. Inparticular, IR laser having a wavelength of from 780 nm to 1200 nm isespecially preferably used.

The exposure mechanism may be any of internal surface drum system,external surface drum system and flat bed system.

Other light sources may also be used for exposure of the lithographicprinting plate precursors. For example, they include various mercurylamps of ultrahigh pressure, high pressure, medium pressure or lowpressure, chemical lamps, carbon arc lamps, xenon lamps, metal halidelamps, visible or IR laser lamps, fluorescent lamps, tungsten lamps, andsunlight.

After exposed to light, the lithographic printing plate precursors aredeveloped. For the developer, preferred is an aqueous alkali solutionhaving a pH of at most 14, and more preferred is an aqueous alkalisolution containing an anionic surfactant and having a pH of from 8 to12. For example, inorganic alkali agents may be used, and they includesodium, potassium and ammonium tertiary phosphates, sodium, potassiumand ammonium secondary phosphates, sodium, potassium and ammoniumcarbonates, sodium, potassium and ammonium hydrogencarbonates, sodium,potassium and ammonium borates, sodium, ammonium, potassium and lithiumhydroxides. In addition, organic alkali agents may also be used, andthey include monomethylamine, dimethylamine, trimethylamine,monoethylamine, diethylamine, triethylamine, monoisopropylamine,diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine,diethanolamine, triethanolamine, monoisopropanolamine,diisopropanolamine, ethyleneimine, ethylenediamine, pyridine. Eithersingly or as combined, one or more of these alkali agents may be used.

The developer to be used for developing the lithographic printing plateprecursors may contain from 1 to 20% by mass, preferably from 3 to 10%by mass of an anionic surfactant. If the amount of the surfactant in thedeveloper is too small, the developability with the developer mayworsen; but if too large, it may cause some problems in that thestrength such as abrasion resistance of the images formed may lower. Theanionic surfactant includes, for example, sodium lauryl alcohol sulfate,ammonium lauryl alcohol sulfate, sodium octyl alcohol sulfate; salts ofalkylarylsulfonic acids such as sodium isopropylnaphthalenesulfonate,sodium isobutylnaphthalenesulfonate, sodium salt of polyoxyethyleneglycol mononaphthyl ether sulfate, sodium dodecylbenzenesulfonate,sodium metanitrobenzenesulfonate; sulfates with higher alcohols havingfrom 8 to 22 carbon atoms such as secondary sodium alkylsulfates; saltsof phosphates with aliphatic alcohols such as sodium cetyl alcoholphosphate; sulfonates of alkylamides such as C₁₇H₃₃CON(CH₃)CH₂CH₂SO₃Na;sulfonates of dibasic aliphatic esters such as dioctylsodiumsulfosuccinate, dihexyl sodiumsulfosuccinate.

If desired, an organic solvent miscible with water, such as benzylalcohol, may be added to the developer. Suitably, the organic solventhas a solubility in water of at most about 10% by mass, preferably atmost 5% by mass. For example, it includes 1-phenylethanol,2-phenylethanol, 3-phenylpropanol, 1,4-phenylbutanol, 2,2-phenylbutanol,1,2-phenoxyethanol, 2-benzyloxyethanol, o-methoxybenzyl alcohol,m-methoxybenzyl alcohol, p-methoxybenzyl alcohol, benzyl alcohol,cyclohexanol, 2-methylcyclohexanol, 4-methylcyclohexanol, and3-methylcyclohexanol. The organic solvent content of the developer ispreferably from 1 to 5% by mass of the total mass of the developer inservice. The amount of the organic solvent in the developer has closerelation to the amount of the surfactant therein. With the increase inthe amount of the organic solvent therein, the amount of the anionicsurfactant in the developer is preferably increased. This is because, ifthe amount of the organic solvent in the developer is increased whilethat of the anionic surfactant is small, then the organic solvent couldnot dissolve in the developer and therefore good developability couldnot be ensured.

If desired, the developer may contain any other additive such asdefoaming agent and water softener. The water softener includes, forexample, Na₂P₂O₇, Na₅P₃O₃, Na₃P₃O₉, Na₂O₄P(NaO₃P)PO₃Na₂; polyphosphatessuch as Calgon (sodium polymethacrylate); aminopolycarboxylic acids(e.g., ethylenediaminetetraacetic acid, and its potassium salt, sodiumsalt; diethylenetriamine-pentaacetic acid, and its potassium salt,sodium salt; triethylenetetramine-hexaacetic acid, and its potassiumsalt, sodium salt; hydroxyethylethylenediamine-triacetic acid, and itspotassium salt, sodium salt; nitrilotriacetic acid, and its potassiumsalt, sodium salt; 1,2-diaminocyclohexane-tetraacetic acid, and itspotassium salt, sodium salt; 1,3-diamino-2-propanol-tetraacetic acid,and its potassium salt, sodium salt), other polycarboxylic acids (e.g.,2-phosphonobutane-tricarboxylic acid-1,2,4, and its potassium salt,sodium salt: 2-phosphonobutanone-tricarboxylic acid-2,3,4, and itspotassium salt, sodium salt); organic phosphonic acids (e.g.,1-phosphonoethane-tricarboxylic acid-1,2,2, and its potassium salt,sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, and its potassiumsalt, sodium salt; aminotri(methylenephosphonic acid), and its potassiumsalt, sodium salt). The most preferred amount of the water softener tobe in the developer varies, depending on the hardness and the amount ofhard water to be used, but in general, it may be from 0.01 to 5% bymass, preferably from 0.01 to 0.5% by mass of the developer.

In case where the lithographic printing plate precursors are developedin an automatic developing machine, the developer used will be fatiguedin accordance with the amount of the precursors processed therewith, anda replenisher or a fresh developer may be supplied to the machine forrestoring the ability of the processing solution in the machine. In thiscase, the replenishment is preferably effected according to the methoddescribed in U.S. Pat. No. 4,882,246. The developers described in JP-A50-26601, 58-54341, and JP-B 56-39464, 56-42860, 57-7427 are alsopreferred.

Thus developed, the lithographic printing plate precursors may bepost-processed with washing water, or a rinsing solution containingsurfactant, or a desensitizer containing gum arabic or starchderivative, as in JP-A 54-8002, 55-115045, 59-58431. These treatmentsmay be combined in any desired manner for post-processing thelithographic printing plate precursors.

In the plate-making method of processing the lithographic printing plateprecursors, if desired, the precursors being processed may be heated onthe entire surface thereof before exposure, during exposure, afterexposure and during development. The heating produces various advantagesin that it promotes the image formation on the recording layer, improvesthe sensitivity and the printing durability, and stabilizes thesensitivity. For further improving the image strength and the printingdurability, it may be effective to treat the entire surface of thedeveloped plates for post-heating or post-exposure thereof.

In general, the heating before development is effected preferably undermild condition at 150° C. or lower. If the temperature is too high, itmay cause a problem of undesired curing reaction in the non-image area.However, the heating after development may be effected under extremelysevere condition. In general, the heating temperature after developmentmay fall between 200 and 500° C. If the heating temperature afterdevelopment is too low, it will be ineffective for enhancing the imagestrength; but if too high, it may cause some problems in that thesupport may be deteriorated and the image area may be thermallydecomposed.

The lithographic printing plate thus obtained through these treatmentsis set in an offset printer and is driven to give a large number ofprints.

Plate cleaners may be used for cleaning the printing plates used forproducing prints. For example, PS plate cleaners heretofore well knownin the art may be used, and they include, for example, CL-1, CL-2, CP,CN-4, CN, CG-1, PC-1, SR, IC (by Fuji Photo Film).

EXAMPLES

The invention is described more concretely with reference to thefollowing Examples, which, however, are not intended to restrict thescope of the invention.

Production Example 1 Production of Specific Alkali-Soluble Polymer (A),P-2

<Preparation of Starting Monomer M-1>

An acetone solution of methyl 4-aminobenzoate (from Wako Pure Chemicals)(302 g) and sodium acetate (from Wako Pure Chemicals) (164 g) was cooledto 0° C., and methacrylic acid chloride (from Wako Pure Chemicals) (220g) was dropwise added to it. The solution was filtered, and theresulting filtrate was put into hydrochloric acid (35 wt. % aqueoussolution) (8 liters), and filtered. The resulting filtrate was dried invacuum to obtain a white solid, starting monomer M-1 having thestructure mentioned below. M-1 was identified through ¹H-NMR and IRspectrometry.

Starting Monomer M-1

Starting Monomer M-2

<Production of Polymer (P-2)>

An N,N-dimethylacetamide (156 g) solution of Light Ester HO-MS (fromKyoeisha Chemical) (22 g), the starting monomer M-1 obtained as in theabove (17 g), starting monomer M-2 having the above-mentioned structure(87 g) and dimethyl 2,2′-azobis(2-methylpropionate) (from Wako PureChemicals) (0.7 g) was dropwise added to N,N-dimethylacetamide (156 g)in a nitrogen atmosphere at 80° C., taking 2.5 hours. After theaddition, this was stirred at 80° C. for 2 hours. After cooled,N,N-dimethylacetamide (446 g), p-methoxyphenol (from Wako PureChemicals) (0.5 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (from WakoPure Chemicals) (155 g) were added to the solution, and stirred at roomtemperature for 12 hours. Next, methanesulfonic acid (from Wako PureChemicals) (98 g) was dropwise added to it at 0° C., and the resultingsolution was put into water (8 liters) stirred vigorously, and this wasstirred for 30 minutes. The white solid formed was taken out throughfiltration and dried to obtain a specific alkali-soluble polymer P-2.

The specific alkali-soluble polymer P-2 was identified through gelpermeation chromatography, acid value titration (with aqueous 0.1 Msodium hydroxide solution), NMR and IR spectrometry.

Production Example 2 Production of Specific Alkali-Soluble Polymer (A),P-18

<Production of Polymer (P-18)>

An N,N-dimethylacetamide (1267 g) solution of Light Ester HO-MS (fromKyoeisha Chemical) (173 g), N-phenylmethacrylamide (from Tokyo Chemical)(242 g), the starting monomer M-2 having the above-mentioned structure(628 g) methacrylic acid (from Wako Pure Chemicals) (43 g) and dimethyl2,2′-azobis(2-methylpropionate) (from Wako Pure Chemicals) (6.9 g) wasdropwise added to N,N-dimethylacetamide (1267 g) in a nitrogenatmosphere at 80° C., taking 2.5 hours. After the addition, this wasstirred at 80° C. for 2 hours. After cooled, N,N-dimethylacetamide (3376g), p-methoxyphenol (from Wako Pure Chemicals) (5.0 g) and1,8-diazabicyclo[5.4.0]-7-undecene (from Wako Pure Chemicals) (1332 g)were added to the solution, and stirred at room temperature for 12hours. Next, methanesulfonic acid (from Wako Pure Chemicals) (841 g) wasdropwise added to it at 0° C., and the resulting solution was put intowater (70 liters) stirred vigorously, and this was stirred for 30minutes. The white solid formed was taken out through filtration anddried to obtain a specific alkali-soluble polymer P-18.

The specific alkali-soluble polymer P-18 was identified through gelpermeation chromatography, acid value titration (with aqueous 0.1 Msodium hydroxide solution), NMR and IR spectrometry.

Other various specific alkali-soluble polymers (A), and comparativepolymers (CO-1) to (CP-8) were produced in the same manner as inProduction Example 1, except that the starting compounds were varied.Their structures are shown below.

Examples 1 to 50, Comparative Examples 1 to 14

(Formation of Support)

<Support 1: Aluminium Support Processed for Anodic Oxidation>

An aluminium sheet (1S grade) having a thickness of 0.30 mm was grainedwith an aqueous suspension of 800-mesh pumice stone, using a #8 nylonbrush, and then well washed with water. This was etched by dipping in10% sodium hydroxide at 70° C. for 60 seconds, and then washed withrunning water, washed with 20% HNO₃ for neutralization, and then washedwith water. This was electrolytically surface-roughened with sine wavealternating current applied thereto under a condition of VA=12.7 V, inan aqueous 1% nitric acid solution. The quantity of electricity at theanode was 300 C/dm². The surface roughness of the sheet was measured andwas 0.45 μm (as Ra). Next, this was dipped in an aqueous 30% H₂SO₄solution, and desmutted at 55° C. for 2 minutes therein. Then, this wasput in an aqueous 20% H₂SO₄ solution at 33° C. with a cathode applied tothe grained surface thereof, and subjected to anodic oxidation for 50minutes at a current density of 5 A/dm². The oxide film thus formed onit had a thickness of 2.7 g/m². This is support 1.

<Support 2>

The support 1 was coated with a liquid composition for undercoatingsurface treatment mentioned below so that the Si content of the coatinglayer could be about 0.001 g/m², and then dried at 100° C. for 1 minute.This is support 2.

(Liquid Composition for Undercoat)

The following components were mixed and stirred to prepare a liquidcomposition for undercoat. After about 5 minutes, the mixture generatedheat, and this was reacted for 60 minutes as such. Then, this wastransferred into a different reactor, and 30,000 parts by mass ofmethanol was added to it.

Liquid Composition for Undercoat Unichemical's Phosmer PE 20 mas. pts.Methanol 130 mas. pts.  Water 20 mas. pts. Paratoluenesulfonic acid  5mas. pts. Tetraethoxysilane 50 mas. pts.3-Methacryloxypropyltriethoxysilane 50 mas. pts.The back of the thus-processed support (the face thereof not coated withthe undercoating composition) was coated with a back-coating solutionmentioned below, using a bar coater, and dried at 100° C. for 1 minutesto form thereon a back-coat layer having a dry coating amount of 70mg/m².

(Back-Coating Solution)

The following components for sol-gel reaction liquid were mixed andstirred, whereupon it generated heat in about 5 minutes. Then, this wasreacted for 60 minutes as such, and a solution A comprising thefollowing components was added to it to give a back-coating solution.

Sol-Gel Reaction Liquid Tetraethyl silicate 50 mas. pts. Water 20 mas.pts. Methanol 15 mas. pts. Phosphoric acid 0.05 mas. pts.  

Composition of Solution A Pyrogallol-formaldehyde condensate resin 4mas. pts. (molecular weight, 2000) Dibutyl phthalate 5 mas. pts.Fluorine-containing surfactant 0.7 mas. pts.(N-butylperfluoro-octanesulfonamidoethyl acrylate/polyoxyethyleneacrylate copolymer: molecular weight, 20,000) Methanol silica sol (fromNissan Chemical Industry: 50 mas. pts. methanol 30 mas. %) Methanol 800mas. pts.

(Formation of Recording Layer)

The surface of the thus-processed aluminium support (the face thereofcoated with the undercoating composition) was coated with a coatingsolution for recording layer mentioned below so that the dry coatingamount could be 1.5 g/m², and dried at 100° C. for 1 minute to form arecording layer thereon. (Coating Solution for Recording Layer) Binderpolymer (in Examples, this corresponds (as in Tables 1 to 8) tocomponent (A)) (B) Ethylenic unsaturated bond-having compound (as inTables 1 to 8) (C) Compound of generating radical by light or heat (asin Tables 1 to 8) (D) Sensitizing Dye (as in Tables 1 to 8) Additive [S](as in Tables 1 to 8) Fluorine-containing surfactant (Megafac F-177 0.03g from Dainippon Ink Chemical Industry) Thermal polymerization inhibitor0.01 g (N-nitrsophenylhydroxylamine aluminium salt) Pigment dispersion(as mentioned below) 2.0 g Methyl ethyl ketone 20 g Propylene glycolmonomethyl ether 20 g (Composition of Pigment Dispersion) Pigment Blue15:6 15 mas. pts. Allyl methacrylate/methacrylic acid copolymer 10 mas.pts. (copolymerization ratio, 83/17 by mol) Cyclohexanone 15 mas. pts.Methoxypropyl acetate 20 mas. pts. Propylene glycol monomethyl ether 40mas. pts.

The binder polymers in Examples in the following Tables 1 to 8 are thespecific alkali-soluble polymers (A) produced in the above-mentionedProduction Examples. These alkali-soluble polymers were tested forstorage stability. Concretely, 25 g of the alkali-soluble polymer to betested was dissolved in 1 liter of an aqueous alkali solution having apH of 12, then sealed up, and stored in an atmosphere at 25° C. for 60days. After thus stored, the solution was visually checked for thepresence or absence of polymer deposition. The alkali-soluble polymersP-1 to P-32 of the invention gave no deposition after stored for 60days. On the other hand, the comparative polymers CP-1 to CP-5 gave somedeposition confirmed through visual observation.

The compounds used for the binder polymer, the ethylenic unsaturatedbond-having compound (B), the compound of generating a radical by lightor heat (C) (radical generator in Tables 1 to 8) and the sensitizing dye(D), and their amount are shown in Tables 1 to 8 below. TABLE 1 (B)Addition- (C) (D) Pro- Staining Polymer Polymerizable RadicalSensitizing Other tec- Resistance in Devel- Binder Compound GeneratorDye Additive tive Sup- Devel- Printing Non-image Light opment (content)(content) (content) (content) (content) layer port oper Durability AreaSource Sediment Example 1 P-1 DPHA C-1 D-2 no yes 1 1  95,000 good 400 ∘(1.0 g) (1.0 g) (0.3 g) (0.1 g) copies Example 2 P-2 U-2 C-2 D-2 S-1 yes1 1 110,000 good 400 ∘ (1.0 g) (0.5 g) (0.3 g) (0.05 g) (0.5 g) copiesExample 3 P-3 DPHA C-1 D-2 S-2 yes 1 1  90,000 good 400 ∘ (1.2 g) (1.0g) (0.2 g) (0.1 g) (0.5 g) copies Example 4 P-4 DPHA C-3 D-2 S-2 yes 1 1101,000 good 400 ∘ (1.0 g) (1.0 g) (0.25 g) (0.08 g) (0.6 g) copiesExample 5 P-5 U-2 C-2 D-2 S-2 yes 1 1 100,000 good 400 ∘ (1.0 g) (1.0 g)(0.3 g) (0.1 g) (0.5 g) copies Example 6 P-16 A-2 C-1 D-2 S-2 yes 1 1 65,000 good 400 ∘ (1.0 g) (1.0 g) (0.2 g) (0.1 g) (0.5 g) copiesExample 7 P-17 A-1 C-1 D-2 S-2 yes 1 1  65,000 good 400 ∘ (1.0 g) (1.0g) (0.2 g) (0.1 g) (0.5 g) copies Comp. CP-1 U-2 C-1 D-2 S-1 yes 1 1 35,000 good 400 x Ex. 1 (1.0 g) (0.5 g) (0.3 g) (0.5 g) (0.5 g) copiesComp. CP-2 DPHA C-1 D-2 S-2 yes 1 1  35,000 stained 400 x Ex. 2 (1.2 g)(1.0 g) (0.2 g) (0.1 g) (0.5 g) copies

TABLE 2 (B) Polymer Addition- (C) (D) Pro- Staining Binder PolymerizableRadical Sensitizing Other tec- Resistance in Devel- (con- CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opmenttent) (content) (content) (content) (content) layer port oper DurabilityArea Source Sediment Example 8 P-6 U-2 C-1 D-1 no yes 1 1 120,000 good532 ∘ (1.5 g) (0.5 g) (0.3 g) (0.08 g) copies Example 9 P-7 U-1 C-1 D-1S-3 yes 1 1  95,000 good 532 ∘ (1.2 g) (0.5 g) (0.3 g) (1.1 g) (0.4 g)copies Example 10 P-8 DPHA C-1 D-1 no yes 2 2  90,000 good 532 ∘ (1.2 g)(1.0 g) (0.2 g) (1.0 g) copies Example 11 P-9 U-2 C-2 D-1 S-4 yes 1 1 97,000 good 532 ∘ (1.0 g) (1.0 g) (0.2 g) (1.0 g) (0.4 g) copiesExample 12 P-10 DPHA C-2 D-1 S-3 yes 2 1 115,000 good 532 ∘ (1.0 g) (1.0g) (0.2 g) (1.0 g) (0.4 g) copies Example 13 P-16 A-2 C-1 D-1 S-3 yes 11  60,000 good 532 ∘ (1.5 g) (1.0 g) (0.3 g) (0.08 g) (0.4 g) copiesExample 14 P-17 A-2 C-1 D-1 S-3 yes 1 1  80,000 good 532 ∘ (1.5 g) (1.2g) (0.3 g) (0.08 g) (0.4 g) copies Comp. Ex. 3 CP-2 DPHA C-1 D-1 no yes2 2  40,000 good 532 x (1.0 g) (0.5 g) (0.25 g) (1.0 g) copies Comp. Ex.4 CP-3 U-2 C-2 D-1 S-4 yes 1 1  32,000 good 532 x (1.2 g) (1.0 g) (0.2g) (1.0 g) (0.4 g) copies

TABLE 3 (B) Polymer Addition- (C) (D) Pro- Staining Binder PolymerizableRadical Sensitizing Other tec- Resistance in Devel- (con- CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opmenttent) (content) (content) (content) (content) layer port oper DurabilityArea Source Sediment Example 15 P-2 A-1 C-2 D-4 no yes 1 1 160,000 good830 ∘ (1.6 g) (0.5 g) (0.25 g) (0.08 g) copies Example 16 P-2 U-1 C-2D-4 no no 1 1  89,000 good 830 ∘ (1.2 g) (0.5 g) (0.15 g) (0.08 g)copies Example 17 P-6 DPHA C-2 D-4 no yes 1 1 140,000 good 830 ∘ (1.5 g)(0.5 g) (0.3 g) (0.1 g) copies Example 18 P-6 U-2 C-2 D-4 no no 1 1 76,000 good 830 ∘ (1.4 g) (1.0 g) (0.3 g) (0.05 g) copies Example 19P-11 DPHA C-3 D-3 no yes 2 2  90,000 good 830 ∘ (1.0 g) (1.0 g) (0.2 g)(0.1 g) copies Example 20 P-12 U-1 C-4 D-4 no yes 1 1 131,000 good 830 ∘(1.2 g) (0.5 g) (0.25 g) (0.08 g) copies Example 21 P-13 DPHA C-2 D-4 nono 1 1  70,000 good 830 ∘ (1.5 g) (0.5 g) (0.20 g) (0.08 g) copiesExample 22 P-14 DPHA C-5 D-4 no yes 1 1  80,000 good 830 ∘ (1.2 g) (1.0g) (0.15 g) (0.08 g) copies Example 23 P-15 A-1 C-6 D-4 no no 2 2 72,000 good 830 ∘ (1.4 g) (1.0 g) (0.2 g) (0.08 g) copies Example 24P-16 A-1 C-2 D-4 no yes 1 1  70,000 good 830 ∘ (1.0 g) (0.5 g) (0.25 g)(0.08 g) copies Example 25 P-16 A-2 C-2 D-4 no no 1 1  60,000 good 830 ∘(1.0 g) (1.0 g) (0.25 g) (0.08 g) copies Example 26 P-17 A-1 C-2 D-4 noyes 1 1  70,000 good 830 ∘ (1.2 g) (1.0 g) (0.25 g) (0.08 g) copiesExample 27 P-17 A-2 C-2 D-4 no no 1 1  60,000 good 830 ∘ (1.2 g) (1.2 g)(0.25 g) (0.08 g) copies

TABLE 4 (B) Polymer Addition- (C) (D) Pro- Staining Binder PolymerizableRadical Sensitizing Other tec- Resistance in Devel- (con- CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opmenttent) (content) (content) (content) (content) layer port oper DurabilityArea Source Sediment Comp. Ex. 5 CP-1 DPHA C-3 D-4 no yes 1 1 50,000good 830 x (1.5 g) (0.5 g) (0.3 g) (0.1 g) copies Comp. Ex. 6 CP-2 U-1C-2 D-4 no no 1 1 20,000 stained 830 x (1.2 g) (0.5 g) (0.15 g) (0.08 g)copies Comp. Ex. 7 CP-2 A-1 C-2 D-4 no yes 1 1 50,000 good 830 x (1.0 g)(0.5 g) (0.25 g) (0.08 g) copies

TABLE 5 (B) Polymer Addition- (C) (D) Pro- Staining Binder PolymerizableRadical Sensitizing Other tec- Resistance in Devel- (con- CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opmenttent) (content) (content) (content) (content) layer port oper DurabilityArea Source Sediment Example 28 P-18 DPHA C-2 D-2 no yes 1 1  95,000good 400 ∘ (1.0 g) (1.0 g) (0/3 g) (0.1 g) copies Example 29 P-19 U-2C-2 D-2 S-1 yes 1 1 100,000 good 400 ∘ (1.0 g) (0.5 g) (0/3 g) (0.05 g)(0.5 g) copies Example 30 P-20 DPHA C-3 D-2 S-2 yes 1 1  90,000 good 400∘ (1.2 g) (1.0 g) (0.2 g) (0.1 g) (0.5 g) copies Example 31 P-21 DPHAC-1 D-2 S-2 yes 1 1  90,000 good 400 ∘ (1.0 g) (1.0 g) (0.25 g) (0.08 g)(0.6 g) copies Example 32 P-22 U-2 C-1 D-2 S-2 yes 1 1  95,000 good 400∘ (1.0 g) (1.0) (0.3 g) (0.1 g) (0.5 g) copies Example 33 P-29 A-2 C-3D-2 S-2 yes 1 1  75,000 good 400 ∘ (1.0 g) (1.0 g) (0.2 g) (0.1 g) (0.5g) copies Comp. Ex. 8 CP-3 U-2 C-1 D-2 S-1 yes 1 1  35,000 stained 400 x(1.0 g) (0.5 g) (0.3 g) (0.5 g) (0.5 g) copies Comp. Ex. 9 CP-4 DPHA C-1D-2 S-2 yes 1 1  35,000 stained 400 x (1.2 g) (1.0 g) (0.2 g) (0.1 g)(0.5 g) copies

TABLE 6 (B) Polymer Addition- (C) (D) Pro- Staining Binder PolymerizableRadical Sensitizing Other tec- Resistance in Devel- (con- CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opmenttent) (content) (content) (content) (content) layer port oper DurabilityArea Source Sediment Example 34 P-23 U-2 C-2 D-1 no yes 1 1  70,000 good532 ∘ (1.5 g) (0.5 g) (0.3 g) (0.08 g) copies Example 35 P-24 U-1 C-2D-1 S-3 yes 1 1  70,000 good 532 ∘ (1.2 g) (0.5 g) (0.3 g) (1.1 g) (0.4g) copies Example 36 P-25 DPHA C-2 D-1 no yes 2 2  70,000 good 532 ∘(1.0 g) (1.0 g) (0.3 g) (1.0 g) copies Example 37 P-26 U-2 C-1 D-1 S-4yes 1 1 120,000 good 532 ∘ (1.0 g) (1.0 g) (0.2 g) (1.0 g) (0.4 g)copies Example 38 P-27 DPHA C-1 D-1 S-3 yes 2 1 115,000 good 532 ∘ (1.0g) (1.0 g) (0.2 g) (1.0 g) (0.4 g) copies Example 39 P-28 A-2 C-2 D-1S-3 yes 1 1  80,000 good 532 ∘ (1.5 g) (1.2 g) (0.3 g) (0.08 g) (0.4 g)copies Comp. CP-3 DPHA C-1 D-1 no yes 2 2  40,000 good 532 x Ex. 10 (1.0g) (0.5 g) (0.25 g) (1.0 g) copies Comp. CP-4 U-2 C-2 D-1 S-4 yes 1 1 32,000 good 532 x Ex. 11 (1.0 g) (1.0 g) (0.2 g) (1.0 g) (0.4 g) copies

TABLE 7 (B) Polymer Addition- (C) (D) Pro- Staining Binder PolymerizableRadical Sensitizing Other tec- Resistance in Devel- (con- CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opmenttent) (content) (content) (content) (content) layer port oper DurabilityArea Source Sediment Example 40 P-18 A-1 C-3 D-4 no yes 1 1 120,000 good830 ∘ (1.0 g) (0.5 g) (0.25 g) (0.08 g) copies Example 41 P-18 U-2 C-2D-4 no no 1 1  70,000 good 830 ∘ (1.2 g) (0.5 g) (0.15 g) (0.08 g)copies Example 42 P-19 U-1 C-2 D-4 no yes 1 1 100,000 good 830 ∘ (1.5 g)(0.5 g) (0.3 g) (0.1 g) copies Example 43 P-19 DPHA C-2 D-4 no no 1 1 71,000 good 830 ∘ (1.4 g) (1.0 g) (0.3 g) (0.05 g) copies Example 44P-22 A-1 C-3 D-3 no yes 2 2  90,000 good 830 ∘ (1/0 g) (1.0 g) (0.2 g)(0.1 g) copies Example 45 P-22 A-1 C-4 D-4 no yes 1 1  90,000 good 830 ∘(1.2 g) (0.5 g) (0.25 g) (0.08 g) copies Example 46 P-29 A-1 C-2 D-4 nono 1 1  70,000 good 830 ∘ (1.5 g) (0.5 g) (0.20 g) (0.08 g) copiesExample 47 P-30 U-1 C-5 D-4 no yes 1 1  80,000 good 830 ∘ (1.2 g) (1.0g) (0.15 g) (0.08 g) copies Example 48 P-31 DPHA C-6 D-4 no no 2 2 72,000 good 830 ∘ (1.4 g) (0.5 g) (0.2 g) (0.08 g) copies Example 49P-32 U-1 C-2 D-4 no yes 1 1  70,000 good 830 ∘ (1.0 g) (0.5 g) (0.25 g)(0.08 g) copies Example 50 P-28 A-2 C-2 D-4 no 1 1  60,000 good 830 ∘(1.0 g) (1.0 g) (0.25 g) (0.08 g) copies

TABLE 8 (B) Addition- (C) (D) Pro- Staining Polymer PolymerizableRadical Sensitizing Other tec- Resistance in Devel- Binder CompoundGenerator Dye Additive tive Sup- Devel- Printing Non-image Light opment(content) (content) (content) (content) (content) layer port operDurability Area Source Sediment Comp. Ex. CP-3 A-1 C-3 D-4 no yes 1 150,000 good 830 x 12 (1.0 g) (0.5 g) (0.25 g) (0.08 g) copies Comp. Ex.CP-4 U-1 C-2 D-4 no no 1 1 20,000 stained 830 x 13 (1.2 g) (0.5 g) (0.15g) (0.08 g) copies Comp. Ex. CP-4 a-1 C-2 D-4 no yes 1 1 50,000 good 830x 14 (1.0 g) (0.5 g) (0.25 g) (0.08 g) copies

The structures of the specific alkali-soluble polymers (A) used inExamples [(P-1) to (P-32)], the comparative binder polymers used inComparative Examples [(CO-1) to (CP-5)], the ethylenic unsaturatedbond-having compounds (B) [(DPHA), (U-1), (U-2), (A-1) and (A-2)], thecompounds of generating a radical by light or heat (C) [(C-1) to (C-6)],the sensitizing dyes [(D-1) to (D-4)], and the additives [(S-1) to(S-4)] are shown below.

(Formation of Protective Layer)

After the recording layer was formed thereon in the manner as above, apart of the samples (as in Tables 1 to 8) were coated with an aqueoussolution of 3 mas. % polyvinyl alcohol (degree of saponification 98 mol%, degree of polymerization 500) so that the dry coating amount could be2 g/m², and dried at 100° C. for 2 hours to form a protective layerthereon.

The process gave lithographic printing plate precursors of Examples andComparative Examples.

(Exposure)

Using different light sources corresponding to the wavelength for theirexposure, the lithographic printing plate precursors fabricated as abovewere exposed to light. For example, any of 400 nm semiconductor laser,532 nm FD-YAG laser and 830 nm semiconductor laser was used, and theywere exposed to light in air.

(Development)

After thus exposed, the samples were developed with an automaticprocessor, Fuji Photo Film's Stablon 900NP. The developer was any of thefollowing developer 1 or 2. The developer bath temperature was 30° C.,and the development time was 12 seconds.

The above process gave lithographic printing plates.

<Developer 1>

This is an aqueous alkali solution comprising the following components.Potassium hydroxide 4 g Potassium hydrogencarbonate 1 g Potassiumcarbonate 2.5 g Sodium sulfite 1 g Polyethylene glycol mononaphthylether 145 g Sodium dibutylnaphthalenesulfonate 55 g Tetrasodiumethylenediaminetetraacetate 8 g Water 750 g<Developer 2>

Fuji Photo Film's DP-4 was diluted to ⅛ with water.

(Printing Durability and Staining Resistance)

Thus obtained, the lithographic printing plate was set in a Lithroneprinter (by Komori Corp.), and the printer was driven to give prints.Every print was visually checked, and the number of good prints withgood ink density was counted. This indicates the printing durability andthe staining resistance of the printing plate tested. The result isgiven in Tables 1 to 8.

(Development Sediment)

The lithographic printing plate precursors (area, 0.88 m²) were exposedto have a non-image area of 0.75 m². Using a developing machine, FujiPhoto Film's LP-1310 equipped with a protective layer-removing device,the exposed plate precursors were developed with a developer having a pHof 11.90 (30° C.) 1200 samples were continuously developed. Thedeveloper used is as in Tables 1 to 8.

After the development, the used developer was visually checked fordevelopment sediment therein. “0” indicates that the development gave nosediment; and “x” indicates that the development gave some sediment. Theresult is given in Tables 1 to 8.

Tables 1 to 8 confirm that the lithographic printing plate precursors ofExamples 1 to 50 in which the polymerizable composition of the inventionwas used in the recording layer had good printing durability and goodstaining resistance, and they did not produce development sediment whilecontinuously processed. On the other hand, however, the lithographicprinting plate precursors of Comparative Examples where alkali-solublepolymers not falling within the scope of the invention were usedproduced development sediment while processed.

The invention provides a polymerizable composition favorable forimage-recording layers of negative lithographic printing plateprecursors. It ensures good printing durability in the image area of theprinting plates produced, not producing development sediment indeveloper where the plate precursors are processed. In addition, theinvention also provides an alkali-soluble polymer favorable for thepolymerizable composition.

The present invention is not limited to the specific above-describedembodiments. It is contemplated that numerous modifications may be madeto the present invention without departing from the spirit and scope ofthe invention as defined in the following claims.

This application is based on Japanese Patent application JP 2003-202919,filed Jul. 29, 2003, the entire content of which is hereby incorporatedby reference.

1. A polymer, which contains a structural unit having a carboxyl grouprepresented by the following formula (1) at a side chain of thestructural unit; and which comprises a functional group represented bythe following formula (2) at a side chain of the polymer, the functionalgroup being capable of changing to an acid group through hydrolysis withalkali:

wherein in formula (1), R¹ represents a hydrogen atom or a methyl group;R² represents a (n+1)-valent organic linking group containing an estergroup represented by —O(C═O)—; A represents an oxygen atom or —NR³—; R³represents a hydrogen atom, or a monovalent hydrocarbon group havingfrom 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5;and in formula (2), Q represents a linking group that links X¹ to a mainchain of the polymer; X¹ represents a protective group hydrolyzable withan alkali aqueous solution having a pH of 10 or more; and when thefunctional group represented by the formula (2) gives -Q-OH afterhydrolysis, the -Q-OH is an acid group having a pKa of 10 or less. 2.The polymer according to claim 1, wherein the functional grouprepresented by the formula (2) is a functional group represented by thefollowing formula (3):

wherein A¹ represents an aromatic group or a cyclo group; n indicates aninteger selected from 1 to 5; X² represents —NR¹R², —SR³, or —OR⁴; R¹ toR⁴ each independently represents a substituent composed of at least oneor more atoms selected from a group consisting of a hydrogen atom, acarbon atom, an oxygen atom, a nitrogen atom, a sulfur atom and ahalogen atom; Y represents a single bond, —O—, or —NR⁵—; and R⁵represents a hydrogen atom or a hydrocarbon atom. 3-8. (canceled)
 9. Apolymer, which contains a structural unit having a carboxyl grouprepresented by the following formula (1) at a side chain of thestructural unit, and which comprises an acid group represented by thefollowing formula (4) having an acid dissociation constant (pKa) of from0 to 11 at a side chain of the polymer:

wherein in formula (1), R¹ represents a hydrogen atom or a methyl group;R² represents a (n+1)-valent organic linking group containing an estergroup represented by —O(C═O)—; A represents an oxygen atom or —NR³—; R³represents a hydrogen atom, or a monovalent hydrocarbon group havingfrom 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5;and in formula (4), X³ represents a single bond that directly links to amain chain of the polymer, or a linking group selected from the groupconsisting of a carboxylic acid ester group (—COO—), an amido group(—CONH—), a hydrocarbon group and an ether group (—O— or —S—); A²-Hrepresents a partial structure that functions as an acid group having anacid dissociation constant (pKa) of from 0 to 11; and m indicates aninteger of from 1 to
 5. 10-15. (canceled)
 16. A polymer, which containsa structural unit having a carboxyl group represented by the followingformula (1) at a side chain of the structural unit, wherein nodeposition is formed, when the polymer is dissolved in an alkali aqueoussolution having a pH of 10 or more and kept at 25° C. for 60 days:

wherein R¹ represents a hydrogen atom or a methyl group; R² represents a(n+1)-valent organic linking group containing an ester group representedby —O(C═O)—; A represents an oxygen atom or —NR³—; R³ represents ahydrogen atom, or a monovalent hydrocarbon group having from 1 to 10carbon atoms; and n indicates an integer of from 1 to
 5. 17. (canceled)18. A polymer, which contains a structural unit having a carboxyl grouprepresented by the following formula (1) at a side chain of thestructural unit, and which comprises an assistant group for dissolutionin an alkali aqueous solution at a side chain of the polymer, wherein nodeposition is formed, when the polymer is dissolved in an alkali aqueoussolution having a pH of 10 or more and kept at 25° C. for 60 days:

wherein R¹ represents a hydrogen atom or a methyl group; R² represents a(n+1)-valent organic linking group containing an ester group representedby —O(C═O)—; A represents an oxygen atom or —NR³—; R³ represents ahydrogen atom, or a monovalent hydrocarbon group having from 1 to 10carbon atoms; and n indicates an integer of from 1 to
 5. 19. (canceled)